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7->''"By opening all eight gates, you could attain power beyond even the Hokage. The only drawback is... you die."''
8-->-- '''Kakashi Hatake''' (on the Hidden Lotus technique), ''Manga/{{Naruto}}''
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10PowerAtAPrice embodied in a single move or technique, a Dangerous Forbidden Technique is an attack that carries a significant risk of harm to it. Maybe it takes a toll on [[CastFromHitPoints the user's body]] or [[WithGreatPowerComesGreatInsanity his mind]]. Maybe it [[TheDarkSide corrupts your essence]] and [[DrunkOnTheDarkSide slowly]] [[SlowlySlippingIntoEvil turns]] [[JumpingOffTheSlipperySlope you evil]]. Maybe it [[SummonBiggerFish summons monsters]] or otherworldly forces that are [[EvilIsNotAToy hard to control]]. Maybe it's just [[BadPowersBadPeople immoral]], or it unlocks a SuperpoweredEvilSide. Whatever the case, there is a very good reason to not use it unless absolutely necessary -- usually when the GodzillaThreshold is reached.
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12Usually, only characters that are already quite powerful are capable of using the move. If another character tried, they would just [[SpontaneousHumanCombustion burst into flames and die]]. You won't see your average {{Mook}} using this. Mooks that can use this are often EliteMooks, {{Instakill Mook}}s, and/or DemonicSpiders.
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14A common way to use this trope is for an OldMaster to teach the technique but insist that the hero [[YouAreNotReady isn't ready to use it yet]]. RuleOfDrama dictates that the hero must keep the technique in his back pocket until such time as he has no choice but to use it. It's like a ForbiddenChekhovsGun, except it has a NecessaryDrawback. Attempting to use it may result in either a [[HeroicRROD Heroic]] or VillainousRROD.
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16In more "realistic" examples involving martial arts, a master may teach the principle of a specific attack to a student, but ban them from trying it on an actual person in practice, because it's just too lethal, and even if you were intentionally trying to pull your blows, you might accidentally kill your partner.
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18Japanese works, especially {{Shonen}}, ''love'' this trope, as it's a perfect manifestation of [[JapaneseSpirit one of the core tenets of Japanese culture]].
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20Compare DeadlyUpgrade, DealWithTheDevil, CastFromHitPoints, CastFromLifespan, CastFromExperiencePoints, ExplosiveOverclocking, SacrificialRevivalSpell, and DeathOrGloryAttack. See also GodzillaThreshold and LethalHarmlessPowers.
21
22!!As this can sometimes be a {{Death Trope|s}}, [[Administrivia/SpoilersOff unmarked spoilers abound]]. [[Administrivia/YouHaveBeenWarned Beware]].
23----
24!!Examples:
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26[[foldercontrol]]
27
28[[folder:Animation]]
29* In ''Animation/{{Tobot}}'', Tobots X and Y are able to combine their powers to use an ability called the Combo Shield, which creates a protective barrier as suggested by its name. Using this power drains X and Y's energy quickly.
30[[/folder]]
31
32[[folder:Anime & Manga]]
33* ''Anime/{{Bakugan}}'':
34** The Ability-X Cards, which force an unstable super-powered evolution on the Bakugan they are used on. In return, the amount of power can become so great that it drives the Bakugan [[WithGreatPowerComesGreatInsanity insane]], and if allowed to grow even further, can cause the Bakugan to [[SuperPowerMeltdown explode.]]
35** The Bakugan Linehalt was imprisoned during his early life due to being last of the Dark Bakugan, a tribe that possessed an ability known only as the forbidden power, but he had no idea what that power actually was, let alone how to use it. When he finally unlocks the forbidden power, it turns out to be an uncontrollable WorldWreckingWave that the user can't stop once they have activated it. Linehalt would have unwillingly destroyed the planet he was on if he hadn't been stopped by the timely intervention of Dragonoid Colossus. He refuses to ever use it again until he figures out that it can also be kicked into reverse and turned into a WorldHealingWave.
36* In ''Manga/BambooBlade'' as well as real-life Kendo, the throat strike is treated this way, because of the high risk of seriously injuring your opponent if done incorrectly. In the series, it is used mostly by morally ambiguous or outright villainous characters, although the main protagonist Tamaki will also attempt to use it when sufficiently provoked or against an especially skilled opponent. In real-world Kendo, throat strikes are only permitted to be used only by high-ranking Kendoka.
37* ''Manga/BlackCat'':
38** Train can only use railguns five times per day. In the final battle, he squeezed out a sixth shot, resulting in him unable to perform it anymore. He's not worried, though, since he has already taken care of the BigBad.
39** Sven's eye ability makes him very tired after using it, which limits him as well, though his ability isn't near as badass.
40* ''Manga/BlackClover'': Deliberately turning into a [[AlmightyIdiot Demon]] is considered to be the most forbiden of magics. The user will gain [[PersonOfMassDestruction immensely destructive magic power]], but will irreversibly [[WithGreatPowerComesGreatInsanity lose their sanity and sense of self]].
41* ''Manga/{{Bleach}}'':
42** Ichigo's fight with Byakuya woke up his [[SuperPoweredEvilSide inner Hollow]] enough for it to want to begin taking over his soul. The more he used his power, the stronger the Hollow became. He eventually learned how to master the hollow, which increased his power in battle. However, it could still take over when he was very close to death, resulting in a truly ghastly outcome for everyone involved. [[spoiler:Only when he learned Final Getsuga Tenshou, which was another example of this trope that destroyed his power after use, was his Hollow fully mastered.]]
43** In his battle with [[MadScientist Mayuri]], Uryuu activated [[OneWingedAngel Letzt Stil]], considered the last resort of the Quincy. His [[OldMaster grandfather]] had taught him the technique with the stipulation that [[YouAreNotReady he should never use it]] until he found something he was willing to give up his power to protect. Uryuu chose to use the technique prematurely, found out that ItOnlyWorksOnce, and [[BroughtDownToBadass lost all his spiritual powers]]. His father [[ParentExMachina Ryuuken]] turned out to have an even ''more'' forbidden technique that could restore Uryuu's powers, but it was a very brutal process. [[spoiler:In the Thousand Year Blood War, we learn about Vollständig, a way to obtain Letzt Stil powers without the one-time-only drawback, but it is forbidden to traditionalists like the Ishidas as unethical.]]
44** Certain [[FunctionalMagic Kidou]] are forbidden. Tessai was exiled with Urahara for using a forbidden Kidou that manipulated space-time. Yamamoto used a forbidden sacrificial Kidou, trading his left arm for a massive pillar of fire in [[KillItWithFire an attempt to kill Aizen]]; as an atonement, he never re-grew it.
45** Captain Komamura's clan has the Human Transformation Technique, which turns them from [[WolfMan anthropomorphic wolves]] into full humans with a power boost. [[spoiler:It requires literally giving up your human heart, and when the technique runs out, leaves the user as a full non-anthropomorphic wolf.]]
46* Parodied in ''Manga/BoboboboBobobo'':
47-->Bobobo: The attack I'll use is forbidden by the Code of the Fist of the Nose Hair! It could cost me my video store membership!
48* [[GravityMaster Chuuya]]'s "Corruption" in ''Manga/BungouStrayDogs'' allows him to manipulate gravitons, turning him into an incredibly powerful combatant with SuperStrength and the ability to throw miniature black holes. The downside is that he also enters an UnstoppableRage which forces him to keep rampaging until he dies of exhaustion. For this reason, he only uses this technique when he's confident that Dazai will be there to use his PowerNullifier ability to stop him once the task is done.
49* In ''Manga/CodeBreaker'', Toki Fujiwara's usage of his Gauss Cannon will damage whatever arm that he uses to fire. This means he can't fire more than twice overall in a fight.
50* {{Parodied}} in ''Manga/DailyLivesOfHighSchoolBoys'' ''High School Boys and the Sure-kill Shot'' skit, when Mitsuo claimed he "sealed" his "reflection shot" because it's too unfair. He's right; the soccer ball reflects because of the piece of plastic he planted on the field. [[ButtMonkey Mitsuo being Mitsuo]], it still got saved by the self-proclaimed NonActionGuy Hidenori.
51* In ''Anime/DenNohCoil'', there's [[spoiler:Imago, which allows the user of it to effectively become a {{Technopath}} within the augmented reality. However, side effects of using it result in damage to one's body, including [[YourMindMakesItReal heart problems and other nasty effects]].]]
52* ''Franchise/DragonBall'':
53** Original ''Manga/DragonBall'':
54*** Tenshinhan's forbidden technique is the Kikoho/Tri-Beam, which will kill him with overuse or otherwise exhaust him to the point of being unable to fight. The attempt that killed him was an attempted RoaringRampageOfRevenge against Nappa that didn't work (mostly because Tien had also lost his right arm and a lot of blood, thus a lot of his strength) and the attempt that drained him to the point of exhaustion was using it over and over in the stronger Shin Kikoho/Neo Tri-Beam format to keep 2nd Form Cell from chasing after Android 18.
55*** The Mafūba/Evil Containment Wave is the technique Master Mutaito used to seal Great Demon King Piccolo. It requires so much ki that it kills the user, as it did to Master Mutaito; when Piccolo comes back, Roshi tries it unsuccessfully and dies as well. It turns out [[spoiler:age and the low amount of ki most humans have may have been a factor; Tenshinhan survived trying to use it, although it still left him completely defenseless.]]
56** ''Anime/DragonBallZ'':
57*** Goku first learned the Kaio-Ken from Kaio-sama/King Kai, a technique that amplifies all of the user's abilities far beyond their natural limits (not just strength, but vision, taste, hearing, etc). On top of that, it can be stacked, applied multiple times to further multiply its effects up to 20 times. The downside is that it places severe strain on the body, risking severe injury or even death the more it's used. Kaio-sama/King Kai warns Goku to never do more than double it. Vegeta proved to be the GodzillaThreshold where Goku used it at triple capacity, which hurt like hell, and then ''quadruple'' during the BeamOWar. After that, Yajirobe made him scream in agony just by patting him on the back. By the time he fought Freeza, he was strong enough that he could use the lower levels without any strain, but Freeza was strong enough that he had to multiply it by ''twenty'' -- the maximum. Not only was it not nearly enough to win, it also left him exhausted and defenseless.
58*** That's not even mentioning the Super Kaio-Ken (stacking the technique with the Super Saiyan form), which was seen only once during his filler arc battle again Paikuhan/Pikkon (though it is mentioned again in ''Dragon Ball Super''). This technique is so dangerously impractical that it results in ''instant'' death if used while alive, and Goku [[ItOnlyWorksOnce can't even use it again]], even while dead. This anime-only usage was the last time it was used in Z, as the various Super Saiyan forms had superseded it in nearly every regard, and combining the two was only practical while dead.
59*** Vegeta has an "Ultimate Final Skill", effectively a SuicideAttack. (Of course, [[SenselessSacrifice it doesn't work on Buu]].) In the games, it's called "Final Explosion" and reduces you to [[HPTo1 a single hit point]]. In ''Super'', he eventually improved it so it wouldn't kill him, but still left him too weak to fight effectively, leaving him as easy prey for Jiren.
60** ''Anime/DragonBallSuper'':
61*** The Mafuba is brought back in an attempt to seal an immortal god, [[spoiler:Future Zamasu]]. None of the characters even mention the possibility of it being lethal and it in no way weakens the character who used it (except in the manga). It's likely that it was fatal for the Muten Roshi back during Dragon Ball either had too low Ki, he was too old and frail despite his expanded lifespan or a combination of the two. It was more likely the former as, when the Muten Roshi is brought in for the Tournament of Power, he pulls it off three times in a row, then two more times later on before he decides to quit. Despite being over 20 years older, his ki had increased greatly, matching that of base form Goku.
62*** Goku's "Super Saiyan Blue Kaio-Ken", where he uses Kaio-Ken while in his Super Saiyan Blue form. It provides a ''massive'' boost to Goku's power, but has a scant 10% success rate and can potentially kill Goku instantly the other 90% of the time. The technique also leaves Goku weakened, in pain, and unable to effectively use his ki afterwards. Like with the original Kaio-Ken, this handicap is either dropped or overcome as Goku uses it more frequently in future arcs.
63*** In the Tournament of Power arc, Basil has one in the form of a PowerUpFood that greatly bulks him up, increasing his abilities exponentially, but also eats away at his stamina, causing his body to seize up and collapse from fatigue after just a few minutes.
64* ''Manga/Eyeshield21'':
65** The "Devil Bat Ghost" technique causes tremendous strain on the user's knees. Hiruma orders Sena to seal the technique from view; Sena originally thinks it's to stop the competition from seeing it until he breaks the order and finds out firsthand.
66** The "Devil Bat Dive" is a rarely-used two-point conversion technique that requires the runner to leap over both lines, spin, and fall into the end zone, carrying a significant risk of injury. Most teams don't bother and just kick the extra point. It's rarely used in [[UsefulNotes/AmericanFootball real life]] for the same reason.
67* ''Manga/FairyTail'':
68** Summoning the Celestial Spirit King is this. The Celestial Spirit King is the most powerful spirit a celestial mage can summon, so powerful in fact that just his appearance counts as an attack! To do so requires a ton of prerequisites, these include:
69*** Having a very high magical energy threshold, usually sufficient to be able to summon and maintain ''three'' Celestial Spirits at once, a feat considered even by the spirits to be dangerous for most Celestial Wizards. After the summoning is done the user, if not outright killed by summoning the King due to magical exhaustion, will still be physically incapacitated due to the strain the summoning magic causes.
70*** The Celestial Spirit user has to sacrifice one of the Twelve Golden Keys to the Zodiac. These keys are super rare as only one key can be in existence on the planet at any time. While the keys ''do'' regenerate in time, there's no controlling where it might end up and since the contract is broken, it's up for grabs.
71*** The User has to have a strong emotional bond with whatever key they sacrifice. Otherwise the summoning will completely fail. [[spoiler:Lucy was in such an emotional state that right after summoning the king her response by one of the demons as to what she had done is to cry uncontrollably and not answer.]]
72*** Even if the summoning IS successful the King is under a very strict time limit. Typically only about 10 to 15 minutes depending on the mage's magic power and his emotional state is directly tied to the mage's emotional state. So if the mage is incredibly upset or angry the king might very well go on a berserker rush against his opponent. [[spoiler:This is exactly what the Celestial Spirit King does in response to Lucy being so upset.]]
73** In the sequel series, the Fifth Generation Dragon Slayers ([[CannibalismSuperpower Dragon Eaters]]) have the ability to activate [[SuperMode Dragon Force]] at will, boosting their powers to levels such that they can overpower even another Dragon Force wielder. However, its use is strictly forbidden by their guild [[spoiler:because it accelerates the process of Dragonization and permanently turns them into dragons, oftentimes turning them into mad beasts that need to be put down.]]
74* ''Manga/FlameOfRecca'': After the Hokage clan are defeated by Oda Nobunaga’s soldiers, desperate to save her infant son, Recca, and to protect the Madogu, Kagero used a forbidden spell to open a time portal and send Recca into the future, at the cost of her becoming immortal and inability to touch her own son (and vice versa).
75* In ''Manga/FullmetalAlchemist'', human transmutation is the sole taboo when it comes to performing alchemy, and rightly so. The law of equivalent exchange is strict -- you must sacrifice equal or greater value, and the value of human life places a horribly high toll on anyone who would dabble in such a practice. While trying to resurrect their mother, Edward lost a leg and Alphonse lost his ''entire body.'' It cost Edward his arm to merely tether Alphonse's soul to a suit of armor in a golem form through a blood seal. And that still wasn't enough for the [[CameBackWrong alchemy to work]]. [[spoiler:Not that it matters as Ed later learns that human transmutation can't bring the dead back to life; what they had done was transfer Al's soul to the collected human body ingredients, with Ed's left leg as payment.]]
76* ''Anime/GargantiaOnTheVerdurousPlanet'' has a BrainComputerInterface between [[AntiHero Ledo]] and [[HumongousMecha Chamber]], which will kill Ledo after a certain amount of time. Normally regulations won't even let Chamber activate it without knowing that Ledo will have access to Galactic Alliance medical personnel immediately afterwards. Ledo uses it in the final episode to keep up with [[spoiler:[[BigBad Striker]]]], but ultimately, [[spoiler:Chamber ejects him and chooses to make a HeroicSacrifice himself]].
77* Almost everybody in ''Manga/GetBackers'' has one. Ginji starts going crazy if he is in his Lightning Emperor mode for too long. Ban can only use his Jagan three times a day, once per person per day. Himiko's acceleration perfume strains her body. Juubei's Black Flying Needles are controlled by a large magnet, and the force of the magnetic field wreaks all kinds of havoc on his body and blinds him early on.
78* In both ''Manga/GetterRobo G'' and its {{expy}} ''Anime/Gekiganger3'', the Shine Spark and the Gekigan Flare are forbidden, as the three pilots have to hit a switch ''at the same time'' to activate the attack or risk destroying the robot.
79* Overuse of power in ''Anime/GiantRobo'' can lead to nasty consequences. A mook burns himself to near-ashes with his pyrokinesis trying to keep his buddies warm, Alberto the Shockwave [[spoiler:breaks apart after absorbing the Monster Sphere's energy field]], and several characters' powers run fatal risks.
80* Towards the end of the Chimera Ant arc of ''Manga/HunterXHunter'', [[spoiler:after his mind finally breaks after finding out Kite was DeadAllAlong, Gon forced himself to grow by Restricting almost all of his inborn talent to age himself to his physical prime, becoming as strong as Meruem himself to kill Neferpitou in the most brutal and horrifying way possible. By the time he was done with [[AmbiguousGender them]], Pitou was a burnt pile of purple paste, and Gon nearly exploded, ending up in a coma and with a missing arm. Although Gon miraculously recovered from the nearly-lethal strain his body was put through thanks to Killua and Alluka/Nanika, arm and all, he's been effectively BroughtDownToNormal, and he can't see nor use Nen anymore]].
81* In ''VideoGame/InazumaEleven'', [[spoiler:Teikoku]] has some hissatsu techniques, explicitly called "forbidden techniques", which are extremely powerful but strain the user's body; a single use is enough to cause searing pain, and three uses in a single match is liable to send the user to the hospital with the possibility of permanent injuries.
82* Manga/{{Inuyasha}} can allow his demonic blood to temporarily dominate him by casting aside [[{{BFS}} Tessaiga]] (or having it stolen); it's a form of SuperpoweredEvilSide. This "demon form" makes him a lot stronger, but his [[DeadlyUpgrade soul decays]] with each use, and he becomes [[UnstoppableRage more bloodthirsty, vicious, and indiscriminate]] the more his demon side takes over. It also becomes easier to activate (but harder to turn off) over time, implying that his demon side will eventually take over completely if he keeps using it.
83* Few would expect this from an anime about the ''circus,'' but the arc of ''Anime/KaleidoStar'' revolved around one of these. There was a Dangerous Forbidden Technique for trapeze and highwire artists, the [[spoiler:Fantastic Maneuvre]], which was ''so'' dangerous and forbidden, Fool refused to even tell Sora what it was because as soon as she heard about it, she would be so obsessed with it that she'd try it even when she wasn't ready, and die. Attempting this Dangerous Forbidden Technique was what killed [[spoiler:Karlos']] best friend and old partner [[spoiler:Aaron Killian]], becoming [[MyGreatestFailure His Greatest Failure]] and turning him into TheAtoner. [[spoiler:And it drives Aaron's son Yuri to seek revenge against Kalos, taking the Stage away from him because he believes he drove his father to basically kill himself.]] Needless to say, by the end of the first part of the series, [[spoiler:Sora and Layla]] perform it successfully. Doing it even once is enough to [[spoiler:cripple an ''already'' injured Layla for life [[CareerEndingInjury and end her circus career forever]].]]
84* In ''Anime/KatanaMaidens'' (a.k.a. Toji no Miko) the Jujō family has a technique for sealing away a particularly dangerous aradama by sending them deep into the Netherworld where one second there is equivalent to many years (millions at least, possibly even a near infinite number of years). However, to use it the user has to go in with the target. Hiyori's mother was stopped from completing it 20 years before the events of the series and still had her life considerably shortened as a result.
85* IN ''Manga/MadeInAbyss,'' [[RobotKid Reg]] has an ArmCannon that he calls the Incinerator, and which can pretty much kill anything that he blasts with it. The problem is, shortly after using it he faints for two hours, leaving him (or, more likely, Riko and Nanachi) in potential danger.
86* It's revealed in ''Anime/MagicalGirlLyricalNanohaStrikers'' that [[FinishingMove Starlight Breaker]] causes considerable strain on Nanoha's body, and that her constant usage of it, as well as her tendency to use {{Deadly Upgrade}}s, contributed to her being critically injured and hospitalized for nearly a year.
87* ''Manga/MagicalGirlLyricalNanohaVivid'': Nephilim Fist uses the principles of Golem Manipulation on the user's own body. This lets Corona, who is a middling martial artist at best, dish out some impressive moves, but comes with the risk of permanent damage -- being able to fight with your arms broken does not mean those selfsame arms don't need medical attention, for example. When Corona tells Nove about this technique, the latter -- understandably -- does not approve.
88* Even in the ''Franchise/{{Gundam}}'' series, this trope has also caused many a hurt for its pilots.
89** In ''Anime/MobileSuitGundamMSIgloo'', the EMS-10 Zudah was a powerful (for its time) Zeonic Mobile Suit with just a [[FlawedPrototype teensy, tiny little flaw]] -- overexerting the engine would cause the Mobile Suit to fly apart. Oh, sure, by revving those engines, you'd get an incredible speed boost, but it's usually not worth losing your life over it.
90** The NT-D ("Newtype Destroyer") system in ''Anime/MobileSuitGundamUnicorn''. Built in to the eponymous Gundam, the system activates if it detects a Newtype (or cyber-Newtype) somewhere in the vicinity. It then releases all of the limiters on the Gundam's systems, directly linking all the suit's functions to the pilot's mind. This allows the pilot to gain extreme reflexes, almost mechanical precision, and even [[spoiler:the ability to hijack Psy-Commu weapons, which are generally a Newtype's most dangerous weapons]]. However, this system can override the pilot's own morals with the system's programming to destroy Newtypes and runs a very real risk of burning out the pilot's mind and causing severe brain damage.
91** In ''Anime/MobileSuitGundamAGE'', Kio views the AGE-FX's [[SuperMode FX-Burst Mode]] as one, as he has recently made the switch to [[TechnicalPacifist technical pacifism]], and he [[MutuallyExclusivePowerups can't use]] the [[AttackDrone precision weapons]] necessary to guarantee the safety of enemy pilots while using that mode.
92** In ''Anime/MobileSuitGundamIronBloodedOrphans'', it's possible to overclock a Gundam's [[BrainComputerInterface Ālaya-Vijñāna System]] to [[SuperMode dramatically increase the suit's performance and reaction time]], but the mental overload from doing so renders the pilot unable to use one or more bodily functions ever again unless they're connected to the machine. [[spoiler:Gundam Vidar]] avoids these drawbacks by [[spoiler:using the Ālaya-Vijñāna System Type-E, which passes the mental strain onto an AI based on [[WetwareCPU Ein Dalton's brain]], which then [[WeaponWieldsYou controls the pilot's body]] to move the machine]].
93** ''Anime/GundamBuildFightersTry'' has "assimilation", a not-very-well-explained phenomenon where a pilot apparently links his mind to his Gunpla, controlling it like his own body and greatly increasing its performance. Downsides? The pilot incurs actual, ''physical'' injuries when the Gunpla is damaged, and on top of that, using this ability is exhausting in the extreme. There is a real risk of receiving permanent or even life-threatening injuries from this, in a sport that's supposed to be completely harmless (at least, to the people playing it).
94** ''Anime/MobileSuitGundamTheWitchFromMercury'': Just piloting a Gundam is this with them banned under the Cathedra Agreement. The Gund format which underlies the technology was meant for human prosthetics, not moving an 18 foot mecha so pilots die quickly from the strain of piloting them. Increasing Permet score boosts performance and the number of drones one can control but also increases the strain even further. The technology is considered cursed and all those involved with it derided as witches. It's implied however that beyond bioethical concerns, [[FantasticRacism the Spacian corporations banning it didn't want Earthians to get a military edge]]. Main character Suletta being able to [[OneHeroHoldTheWeaksauce pilot her Gundam with no visible side effects]] is shocking to everyone. [[spoiler:As the series continues, it turns out that the Aerial is PoweredByAForsakenChild]].
95* Part of Izuku's CharacterDevelopment in ''Manga/MyHeroAcademia'' is to stop treating [[SuperpowerLottery One For All]] like this trope. Prior to developing the "One For All: Full Cowl", Izuku would pour his power into one extremity, which would deliver devastating blows at the cost of wrecking that extremity. It got to the point where resident healer Recovery Girl put her foot down and refused to treat ''any'' One For All user due to Izuku relying on her healing to mitigate his recklessness. Under "Full Cowl", he instead focuses that power through his entire body and draw out a certain percentage so he isn't wrecking his body. It's still this trope if he goes over a certain percentage, though, but he works to steadily push that percentage upwards. Also, one of the abilities in the One for All package, Gearshift, is treated this way because of its growth into a reality warping power and because too much use causes oxygen deprivation and can harm his body.
96* ''Manga/{{Naruto}}'' is rife with these.
97** A subset of the Shinobi arts are called the ''Kinjutsu'' -- literally "forbidden techniques". For one reason or another, they cannot be taught or used by the commanding shinobi. Some fatally harm the user, like the Shadow Clone Jutsu, which creates perfect {{Doppelganger}}s who [[CastFromHitPoints take an equal portion of their user's chakra]], which is eventually fatal if too many are created at once and/or the sheer backlash the user suffers if too many are killed at once; a version of this is Naruto's SignatureMove, although Naruto has a superhuman chakra reserve ''and'' a [[EldritchAbomination Tailed Beast]] that can handle it. Others are considered unethical, like the Edo Tensei, which [[RiseFromYourGrave resurrects the dead]] at the cost of another HumanSacrifice. Edo Tensei is particularly powerful (effectively giving you a NighInvulnerable army of TheUndead), which increases the temptation to use it, only for the user to find that at its most powerful, [[spoiler:its creations might escape from the user's control]]. Just using a ''kinjutsu'' is not a crime however (only the effect may be), and a few are taught in the course of the plot. So they are not so much "forbidden" but rather "regulated". For example, the Shadow Clone Jutsu can normally only be safely used by Jonin-level shinobi.
98** Initially, Sasuke's Chidori is only supposed to be used twice at a time. The third time he used it, he would have died if he didn't have a cursed seal which nearly [[GrandTheftMe took him over]]. Since then, he increased his own chakra capacity to the point that he can spam it without any ill effects.
99** Kakashi had two forbidden techniques: Raikiri, an enhanced Chidori that requires a [[MagicalEye Sharingan]] to be used effectively; and Kamui, which [[OneHitKill sucks anything he looks at into another dimension]]. Both are limited by chakra capacity, and the second one deteriorates the eyesight of said eye. He figured out how to increase his chakra capacity (and taught Sasuke how as well).
100** Naruto gets his [[BlowYouAway Wind Style]]: [[RazorWind Rasenshuriken]], in the second half of the manga. It's so powerful that it causes widespread cellular damage to the arm he executes it with, including the chakra pathways. The damage is microscopic, so healing jutsu can't repair it, and Naruto's own HealingFactor is so overworked that it [[CastFromLifespan reduces his lifespan]]. Tsunade tells him not to use it again. Then he masters his [[SuperMode Sage Mode]] and perfects it to the point that he can throw it and nullify the risk to himself.
101** Kurama is essentially a SuperPoweredEvilSide; calling upon his power too deeply can also shorten Naruto's lifespan. Naruto instead winds up [[spoiler:befriending him, which allows him access to his full power without having to physically transform.]]
102*** [[spoiler:In ''Manga/{{Boruto}}'', Kurama reveals another one: Baryon Mode. This grants Naruto immense power, beyond even Six Paths Sage Mode in terms of physical strength and speed, but this comes at the cost of Kurama's life. The only silver lining is that because Kurama's chakra was merely used up rather than forcibly removed, it is not fatal to Naruto.]]
103** Tsunade's regeneration jutsu [[CastFromLifespan shortens her lifespan]] as well, due to the Hayflick limit.
104** Lady Chiyo's clan dabbles with using chakra "strings" to control life-size puppets (and in some cases, assist a human by adding their reflexes to the subject's). They began work on Kishou Tensei, a jutsu to truly breathe life into puppets, but stopped when they discovered it had a nasty side-effect of (you guessed it!) killing the user. It turned out Kishou Tensei could heal almost anything, including otherwise lethal injuries and even death. Unfortunately, to do so, [[CastFromLifespan it used the life energy of the user]], along with their chakra, so using it even in the normal way would be highly taxing for the body. And if they used it to revive someone who died, [[EquivalentExchange they would die in their stead.]] [[spoiler:Chiyo winds up [[HeroicSacrifice using it]] to resurrect Gaara after his death due to Shukaku's removal.]]
105** Those with the Rinnegan can use a similar jutsu to Kishou Tensei, but much more powerful, Gedō: Rinne Tensei/Outer Path: Rinne Rebirth. It is capable of resurrecting large groups of people at once, [[HeroicSacrifice at the cost of the user's life.]] [[spoiler:Nagato used it [[RedemptionEqualsDeath to revive those he killed during his assault on Konohagakure, dying in the process]].]]
106** Pain has been shown to have [[spoiler:an ''[[SphereOfDestruction incredibly]]'' powerful version of his Shinra Tensei/Almighty Push that takes off years of his life but can destroy an entire city in one blast. And he uses it on Konoha.]] Nagato, on the other hand, is [[spoiler:an Uzumaki, which means he has his clan's longevity]], so he can use it with reduced risk.
107** The Shiki Fujin/Reaper Death Seal summons [[TheGrimReaper a Shinigami]], who takes [[YourSoulIsMine both your soul]] and [[TakingYouWithMe your opponent's]] and forces them to fight forever in its stomach. The Uzumaki created a mask that allowed one to free the consumed souls, but it required its wearer to commit {{Seppuku}} to do so.
108** The Mangekyou Sharingan is an enhanced version of the Sharingan that grants all manner of nifty new powers like [[MindRape Tsukiyomi]], [[{{Hellfire}} Amaterasu]], [[InstantArmor Susanoo]], [[spoiler:Kamui]] and [[MoreThanMindControl Kotoamatsukami]], but each use of said techniques causes the user to slowly go blind (which eventually removes the ability to use said techniques entirely) and rapid and continued use accelerates the process. Sasuke only had his for a matter of ''days'' at most before his constant and reckless use almost blinded him literally. The only ways to avoid this [[spoiler:are to upgrade to the ''Eternal'' Mangekyou Sharingan, which requires obtaining a close relative's Mangekyou Sharingan to replace your own, as Madara and Sasuke did, or have Hashirama's [[HealingFactor Senju cells]] to regenerate the deterioration, which is what Obito relied on with his remaining eye.]]
109** [[spoiler:Izanagi]] allows users to cast genjutsu on ''themselves'' that can briefly override reality. As a tradeoff, [[spoiler:the eyes used to cast the genjutsu will be permanently blinded.]] The only workaround to this seems to be [[spoiler:possessing the incredible regenerative properties of Hashirama's Senju cells, as Madara was only able to restore the sight of his sacrificed eye by incorporating said cells and awakening the Rinnegan. Also, combining Izanagi and Senju cells extended its duration up to a whole minute per eye]]. Because of this, the Uchiha declared it a Kinjutsu, along with its counterpart, [[spoiler:Izanami, which trapped its target in a StableTimeLoop until they accepted the outcome they were trying to avoid. Even Edo Tensei-revived shinobi aren't immune to the blinding, as Itachi showed]]
110*** To further elaborate on the [[spoiler:Izanami, while the Izanami was developed as a direct counter to the Izanagi (and Sasuke even said it was stronger than it), having a genjutsu that could be escaped from with relative ease during a combat situation was considered too dangerous. Which is why it's forbidden]]
111** The cells of Hashirama Senju, the First Hokage are both this and a potential DeadlyUpgrade. They give those who are spliced with them a tremendous HealingFactor, capable of regenerating missing limbs and otherwise irrepairable organs, like the eyes. They also give those with them the ability to use Hashirama's one-of-a-kind Kekkei Genkai, Mokuton/Wood Style. Unfortunately, the sheer vitality of his cells could overwhelm their user if they overexerted or were simply incompatible, turning them into trees. Orochimaru once experimented with 40 children by injecting them Hashirama's DNA, and all but one of them became trees sooner or later. [[spoiler:The SoleSurvivor was Yamato.]]
112** The Eight Inner Gates (as referenced in the page quote) is a technique that grants exponentially greater strength as each gate is opened, but with increasing strain on the user's body; Rock Lee was almost permanently crippled by using five of them. If all eight are opened, the user becomes physically stronger than any human could be for a few minutes, though the cost of this is [[DeadlyUpgrade dying shortly after]]. When [[spoiler:Guy]] uses all eight gates he becomes more powerful than even [[spoiler:Madara Uchiha, who was hosting the Juubi to boot]], after which his body is so overheated that it starts dissolving into ash while he's still alive. [[spoiler:Naruto stops him from dying, but he's still in a wheelchair years later, as trying to use the leg he nearly killed Madara with causes him extreme pain.]]
113** Chouji's clan have three FoodPills that each boosts their Chakra massively but have worsening side effects with the final one being fatal due to converting all of their fat cells into Chakra. Chouji survives thanks to Tsunade and a Nara clan medical book.
114* ''Manga/NegimaMagisterNegiMagi'''s version of BlackMagic seems to act like this. The first time we see it used is when Jack Rakan demonstrates it for Negi and nearly kills himself in the process. Negi then starts undergoing training so that he'll be able to use it safely. We don't see the real direct consequences of Dark Magic, though, until [[spoiler:Negi basically overdoses on magic and is forced to fight his EnemyWithin; even if he wins, he won't exactly be human anymore.]]
115* Parodied in ''Manga/NinjaNonsense'', where the technique that has been "banned ten years ago because it was so dangerous" is [[DuctTapeForEverything duct tape underpants]].
116* ''Manga/OnePiece'':
117** In general, ''any'' ability gained by Devil Fruit is a dangerous technique. While some have specific drawbacks, they all share one: the user permanently [[SuperDrowningSkills loses the ability to swim.]] Considering that this is an OceanPunk series, that's a potentially lethal side effect. Many pirates are aware of this and use the stuff anyway.
118** Trafalgar Law's Devil Fruit, the Op-Op Fruit, allows the user to perform an "Immortality Operation" [[ItOnlyWorksOnce on a single person]]. It grants the target eternal youth, but it costs the user his own life.
119** The Alabasta arc introduces Hero Water (or Fatal Elixir), which massively increases all the drinker's physical abilities for five minutes before killing them.
120** The Skypeia arc introduces the Impact Dial, which absorbs any force that strikes it and deals it back to the attacker but also causes a great deal of pain to the wielder's arm. Its cousin, the Reject Dial, multiplies the counter-force by ten. Wiper, a character intent on killing the BigBad of that arc with the Reject Dial, uses it three times and escapes alive despite massive damage.
121** Luffy's "Gear" techniques are his SuperMode, and they all qualify.
122*** Gear Second allows Luffy to use his legs as a pump to accelerate the blood flow around his body, dramatically increasing his strength and speed. It would kill a normal human, but RubberMan Luffy can handle it, although it does affect his lifespan. Luffy's a {{Determinator}}, though, so that doesn't stop him that often.
123*** Gear Third is the next level up; he blows air into his bones, which enlarges his body and makes him that much stronger. However, after only a couple of attacks, the effect would wear out, the air would leave his body, and Luffy would now be Chibi-fied and vulnerable. He learned how to avoid that after the TimeSkip, which introduced...
124*** Gear Fourth, where he [[spoiler:inflates his muscles rather than his bones and augments his whole body with Armament Haki.]] This is much stronger than ever Gear Third, and he can even [[spoiler:use it to fly.]] But like Gear Third, it has a time limit, after which Luffy becomes vulnerable [[spoiler:and cannot use Haki for ten minutes.]]
125** Chopper's Monster Point form comes from overuse of the Rumble Ball, which allows him to expand his MultiformBalance to seven forms rather than the standard three. The Rumble Ball's effect is already only three minutes, and he can have only one every six hours. If he uses two, he loses control of his transformations. If he uses three, he activates Monster Point, which turns him into an indiscriminate berserker who could {{curb stomp|battle}} either his enemies or his allies. It's also potentially fatal and knocks Chopper out of commission for a while, although he gets a better handle on it post-TimeSkip.
126*** To be more clear: post-TimeSkip, just eating ''one'' Rumble Ball triggers Monster Point, but Chopper stays in full control the entire time. However, the form automatically deactivates after three minutes, after which Chopper is unable to move for a long time. In the Wano arc, BoxedCrook Caesar Clown helps Chopper improve the Rumble Ball further, multiplying its runtime by ten and reducing the recovery period after reverting to about 15 minutes...except that for those 15 minutes, Chopper is reduced to a few inches tall.
127** Rob Lucci's Rokuogan (or Six King Gun) strikes his opponent with a shockwave comparable to that of a Reject Dial, but using it expends a ridiculous amount of energy. Overuse of the technique was enough to give Luffy a narrow window to defeat him.
128** The Energy Steroids from the Fishman Island arc give the user extreme power, endurance, and stamina, but at the expense of his lifespan [[WithGreatPowerComesGreatInsanity and possibly his sanity as well.]]
129** Minks are able to undergo a transformation into an extremely powerful SuperMode known as Sulong by looking at a full moon, but unless specially trained, they go into a berserk state similar to Chopper's Monster Point pre-TimeSkip where they are a danger to friend, foe, and even themselves, as they can literally fight until they die of exhaustion. Even when trained to keep themselves under control, maintaining Sulong takes a lot of energy, so they can only use it for a few minutes at a time.
130** During the Wano Arc, Zoro is critically injured in the middle of the climactic battle and can't even move anymore. He allows himself to be injected with an experimental medical serum that will temporarily heal him up in only a few minutes, but make his post-battle recovery much worse, just to get back into the fight.
131* ''Manga/OutlawStar'''s Caster gun fired spiritual Caster bullets. Each type was represented by a number, although their differences were never fully established. Eventually, Gene realizes that three numbers never come up, so he tracks down the gunsmiths who make these bullets. They each give him one, but they explain that since they draw on the gunner's soul (there being so little mana left in the universe), if he fires all three, he will die. Sure enough, he needs all three, and sure enough, [[spoiler:he dies along with his enemy, but he was in the Galactic Leyline, which noticed that ''everyone'' inside was dead and performed an AutoRevive.]]
132* Everyone seems to have one in ''Manga/ThePrinceOfTennis'': Tezuka Phantom and Zero Shiki Serve, Ryoma's Cyclone Smash, Atobe's Tannhauser Serve, Sanada's Rai, you name it. The most powerful, though, is "Dash Hadoukyuu", [[TheBigGuy Kawamura's]] most powerful shot [[spoiler:until Final Hadoukyuu]]. The original Hadoukyuu already puts a great deal of strain on the arm, while the Dash Hadoukyuu is restricted to once per match. [[spoiler:Naturally, he breaks this rule against Gin Ishida]].
133* In ''Anime/{{Raideen}}'', the titular mecha has the powerful "God Voice" attack, which ends up ruining his vocal cords every time he does it. In the ''VideoGame/SuperRobotWars'' games, Akira will actually end up being unable to speak if you use this too many times before a certain point.
134* ''Manga/RamenFighterMiki'' parodies this trope when Kankuro tries to decide what thing he would imitate to beat Miki.
135--> '''Kankuro:''' [[PowerCopying As long as I imagine myself as something before training, I’ll gain both confidence and strength,]] [[VerbalTic nya]]. What should I imagine myself as next, [[VerbalTic nya]]?\
136'''Akihiko:''' Shouldn’t you have already decided on that?\
137[''Flashback of Miki being {{Curb Stomp Battle}}d by her mother, a fat restaurant hostess.'']\
138'''Kankuro:''' That’s impossible, [[VerbalTic nya]].
139* ''Manga/RanmaOneHalf'':
140** Ryoga Hibiki's "Shishi Hōkōdan" is a KiManipulation fueled by the user's [[EmotionalPowers depression and melancholy]]. Ryoga tries to increase its power by becoming even ''more'' depressed. Ranma tries this when fighting him but eventually sees the flaw in this strategy -- the winner of the fight will be happy enough to depower it -- and thus creates a much safer (but just as powerful) technique based on boundless confidence.
141** [[CrouchingMoronHiddenBadass Genma]] developed two such techniques: the [[CombatPragmatist Yamasenken]] and [[StealthRun Umisenken]]. Unusually for this series, they're both lethal and can be used for [[AndShowItToYou ripping out an opponent's heart]], strangling him, or cutting him into itty bitty pieces. Genma was loath to teach Ranma anything about them, on the ground that they were far too dangerous; he only acquiesced when he learned that Ryu Kumon was using the Yamasenken. Ranma duelled Ryu with the stipulation that if he won, Ryu would seal the techniques forever. Then Ranma learned the ''other'' reason they're forbidden techniques: [[spoiler:Genma created them based on the two contrasting forms of ''burglary''.]]
142** Parodied with Happosai's "Happo Fire Burst", which was sealed away for being too destructive... when he accidentally [[DirtyOldMan burnt up a recently-stolen brassiere with it]]. He unseals it to punish Soun Tendo and the Saotomes, when it turns out to be nothing more than a fancy name for throwing homemade firecracker bombs around ([[ImprobableWeaponUser which is no less effective]]).
143* ''Anime/RebuildOfEvangelion'' brings us [[UnstoppableRage Beast Mode]], which grants the Evangelion a power boost at the cost of potentially contaminating its pilot's mind. It's also shown to be a very PainfulTransformation, for both the Eva and the pilot. Further, even if it is successfully activated, the pilot loses all reason and is only capable of fighting like an enraged animal.
144* ''Manga/RurouniKenshin'':
145** Kenshin fighting style, Hiten Misturugi Ryuu, has an ultimate technique that involves putting the user in significant danger. If you hesitate for even a moment, you either die or lose your leg. If you don't hesitate, you might still lose your leg. But overall, the style as a whole takes its toll on Kenshin, who [[spoiler:winds up having to retire from swordsmanship for good]]. Shishio used this technique as well, and [[spoiler:as he was in a full-body bandage, he died of heat exhaustion after 15 minutes]].
146** Sanosuke's [[MegatonPunch Futae No Kiwami]] becomes one over time due to its overuse. His hand injury was said to be even worse than the damage Kenshin suffered against Shishio. Though his hand never really heals, he finds ways to minimize the damage.
147** It is appropriate to note that the two aforementioned techniques (Hiten Mitsurugi Ryuu and Futae no Kiwami) were taught by fighters with [[HeroicBuild the]] [[MusclesAreMeaningful bodies]] of {{Lightning Bruiser}}s (Hiko Seijuro and Anji, respectively), while Kenshin and Sanosuke are very lightly-built by comparison. SurprisinglyRealisticOutcome, in a way, is at play--in that people without the body mass and build to use these straining techniques are likelier to ruin their bodies in the process.
148* ''Franchise/SailorMoon'':
149** Sailor Pluto will die if she uses her power to stop time, and Sailor Saturn will die if she uses her power of destruction. [[spoiler:They're forced to break this taboo in the various series -- in the manga and ''Anime/SailorMoonCrystal'', Pluto breaks her taboo to stop Prince Demando from colliding the past and future Silver Crystals and causing a TimeCrash while in the original anime, she breaks the taboo to allow Uranus and Neptune to enter Mugen Academy and reach Mistress 9 before their helicopter is destroyed; in all three incarnations, Saturn uses her power to stop Pharaoh 90 and allow Sailor Moon to restore everything. In the manga and ''Crystal'', Pluto ends up being reborn as Setsuna Mei'oh and returns to action during the Infinity Arc while in the original anime, her fate is left ambiguous and she sits out ''[=SuperS=]'' ([[Anime/SailorMoonSuperSTheMovie Unless its movie is canon]], in which that was the only time she showed up in ''[=SuperS=]''); Saturn is reborn as a baby in all three versions and doesn't return until the final arc with Pluto]].
150** [[Anime/SailorMoon The anime]] gives us the Silver Crystal, which at full power equates to a KamehameHadoken and kills the user nine times out of ten. But they get one lash wish, which is usually enough to reverse it; Moon got her normal life back and it was enough for her, Mamoru, and the Senshi to be revived, even if with TraumaInducedAmnesia until some time later.
151* ''Manga/SaintSeiya'':
152** Dragon Saint Shiryu is warned by his master never to push his fighting technique beyond a certain limit, lest he unleash the "Ultimate Dragon", basically sending himself and his opponent into orbit. Of course, Shiryu ''does'' end up unleashing the "Ultimate Dragon". [[spoiler:But he doesn't die. His opponent Shura has a last-minute change of heart and manages to send him back to Earth with just a very well-timed kick. Seriously.]] That being said, the technique was never used again in the manga. In the [[{{Filler}} next arc]] of the anime, Shiryu attempted it again as a last resort move, but stopped when doing so would destroy a MacGuffin that was needed.
153** Athena Exclamation is a technique so devastating, so powerful, it has the power to annihilate the Earth. Therefore, it was declared taboo by Athena's Saints. It consists of three Gold Saints focusing all their [[BattleAura Cosmo]] into a single point, discharging a blast with the same power as the Big Bang itself. Naturally, it was used in the final arc. And once ''that'' taboo [[GodzillaThreshold was broken]], it was used twice more -- by [[OhCrap two opposing trios of Gold Saints]].
154* Jin from ''Anime/SamuraiChamploo'' learns his master's Dangerous Forbidden Technique only by word of mouth, along with (needless) explanation of its danger. During his final episode duel, he has to use it in battle. [[spoiler:He allows himself to be stabbed and takes advantage of his opponent's position at his side and effective defenselessness (as his sword is stuck in Jin) to strike him down.]]
155* ''Anime/SenkiZesshouSymphogear'': Using a symphogear at all can be dangerous. If the user’s synch rate isn’t high enough, they may only be able to fight for a few minutes before they start bleeding from the mouth and eyes. Likewise, singing The Ultimate Song unleashes a massive amount of power with a proportionate toll on the user’s body; Tsubasa’s naturally high synch rate let her survive it, give or take a few days in the hospital, while Kanade’s was so low that it burnt her to ash. [[TheHero Hibiki]] was an exception for the first few seasons because her gear was a part of her body, which not only let her survive the technique but absorb it from others for a CombinedEnergyAttack.
156* ''Manga/SoulEater'':
157** Using Tsubaki's [[spoiler:Uncanny Sword mode]] takes a toll on Black☆Star's health. Early on, he can only maintain it for a short duration before passing out. At one point, the normally submissive Tsubaki refuses to use it out of fear for her partner's well-being. [[spoiler:Eventually, he finds a way around this, at which point the mode apparently stops having a dangerous effect. Really, all it needed was for Black Star to ''listen'' to others (namely Tsubaki) in order to have a chance of working out the technique, rather than assuming it took only physical strength. Being [[JerkWithAHeartOfGold a decent guy really]], he manages it.]]
158** In the anime, Soul's black blood allows him to give his allies a power boost with Soul Resonance, but every time he uses it the madness gains more control of his body and mind (represented by the Little Ogre inside his mind growing bigger, until he's bigger than Soul and able to take over).
159* Late in ''Anime/TekkamanBlade'', D-Boy finds that the Tekkaman transformation is slowly destroying his body. Later, he apparently gets better by "evolving" his transformation into the more powerful Blaster mode. Unfortunately, that turns out to be a better example of this, since now he's losing memories whenever he transforms, which for him is even worse. [[spoiler:While he ultimately loses all of his memories, which leaves him paralyzed and speechless for a while, D-Boy survives and eventually rebuilds a new life on Earth.]]
160* ''Manga/UshioAndTora'':
161** The Demon-Submitting Technique Iguri from a manga-only arc requires: 1) a powerful buddhist weapon to channel dharmic energy, 2) two monks with enough dharmic powers, one to hold the weapon and one to start transmitting the energy surge and 3) a row composed of huge number of people (the passengers of a whole train) holding hands in a human chain to deliver and develop the dharmic energy from one bonze to the other: they can be laymen, but still the surge is very painful and can temporarly cripple people, the effect worsening the closer they are to the last monk. That being said, the resulting technique is said to be powerful enough to slay even the [[{{Satan}} Demon King of the Sixth Heaven]].
162** For Ushio, removing the red tassel from the Beast Spear or willingfully give in more of his soul to it: the resulting strength is so much that Ushio was able to slay a fallen god of the land with it, but the usage quickly weakens his spirit and slowly turns him into a soulless beast.
163* {{Parodied|Trope}} in ''Manga/TheWorldGodOnlyKnows'': Suffering from DatingSim withdrawal, Keima resorts to "Capturing God Mode" in order to clear his backlog, playing six games at once at blinding speed while still able to react emotionally to each one. He claims that an hour will cause the user to lose three years of his life (or at least be tired enough to feel that way). He eventually passes out under the strain. That doesn't stop him from hitting ''24'' games at once later in the series.
164* ''Anime/YuGiOh'':
165** Industrial Illusions has the [[IdiotBall decidedly odd practice]] of designing cards "too powerful and dangerous to be used," requiring them to be sealed somewhere or guarded to keep them from falling into the wrong hands. They ''always'' fall into the wrong hands. (It's little wonder why the game is such SeriousBusiness in this series.) Yugi himself seems to be the only one who recognizes the potential danger of these cards; the first thing he says upon winning Osiris from Strings is, "I must be ''very'' careful with this."
166** ''Anime/YuGiOhGX'' has the "Cyber Legacy", which Kaiser Ryō inherited. Normally, he and the other duelists in the Cyber-Style dojo (yes, the Legacy is apparently so powerful, you need to train in a dojo to properly duel with it) practice the normal Cyber-Style, but there's another set of cards known as the Cyberdark-Style that's sealed away from even the Legacy's heir due to its immense and dangerous power. [[spoiler:Ryo learns just why it's so dangerous and forbidden [[ThisIsYourBrainOnEvil the hard way]].]]
167** In the real game, cards deemed too powerful are forbidden from official tournaments. Unfortunately, they're not always consistent as to what exactly is "too powerful".
168* In ''Anime/YukiYunaIsAHero'' there's the Mankai, a SuperMode the Heroes can activate to channel the power of the Shinju itself. However, it comes at the cost of a sacrifice, [[spoiler:namely, one of the Hero's bodily functions, such as the loss of the sense of taste, voice, or ability to use a limb.]]
169* In ''Manga/YuYuHakusho'', Hiei's Dragon of the Darkness Flame is an absurdly powerful technique that summons a dragon made of insanely hot hellfire that incinerates pretty much any enemy that comes into direct contact with it, even fire-resistant demons. The catch? If the user isn't sufficiently powerful, the dragon can turn on the caster and devour him. And the first time Hiei used it, he had to offer his right arm as a sacrifice. [[spoiler:Also subverted, as the one moment the attack ''is'' turned on Hiei, he's become powerful enough to control it, not only surviving but also temporarily absorbing it into his body, becoming much, much more powerful.]]
170** Younger Toguro can regulate how much strength he uses, becoming more monstrous the closer he gets to 100% strength. Then there's his "100% of 100% strength" (dubbed "120%" in one videogame) form, where he gets even stronger at the cost of losing energy at an unsustainable rate, which requires him to constantly drain the soul of nearby living things to keep the form active.
171* ''Anime/ZoidsNewCentury'' has a mecha version: Among the three alternate armours available for the Liger Zero is the [[MechaExpansionPack Panzer armour]], effectively turning the Liger into a walking tank with [[WaveMotionGun huge guns]] and [[MacrossMissileMassacre lots and lots of missiles]]. However, it's so [[DeadlyUpgrade heavy and power-consuming that the Liger can barely move and quickly overheats just from wearing the armour]]. It has to be ejected on the battlefield right after each use to avoid melting the Liger Zero and cooking Bit alive.
172[[/folder]]
173
174[[folder:Comic Books]]
175* In the ''ComicBook/BuffyTheVampireSlayer'' prequel comics, there are dark magicks that the Watchers are forbidden to use. Someone does it anyway and gets revealed by Giles. But Giles had also used a forbidden technique to reveal the guy, which is why he gets put through a torturous test that either drove everyone else who took it insane or killed them outright.
176* When put into a situation where there's nothing around that he can manipulate with his magnetism abilities, ComicBook/CosmicBoy can use the iron in his own body. This is understandably dangerous, painful, and usually very limited, but he can usually find something else to use since villains tend to underestimate just how little he needs to work with.
177* In the Marvel universe, there exists a weapon called the Ultimate Nullifier which can RetGone anyone or anything the user chooses. But if the user doesn't visualize the target properly, then ''the user'' is erased. This is possibly the only weapon that can truly defeat ComicBook/{{Galactus}}. (Possibly. He is known to be afraid of it, at least. Whether any mortal would actually be capable of perfectly visualizing Galactus is dubious. However, in his, and its, first appearance, he worried more that Reed would unmake ''the whole universe'' trying, and he immediately decided to leave Earth alone.)
178* The Human Torch of the ''ComicBook/FantasticFour'' can release a blast of nova-intensity heat, which was very dangerous to do in his earlier days (one issue even stated that releasing it at maximum power would instantaneously kill every living thing in the same hemisphere of Earth as him). Later subverted as he learned to control it better, making collateral damage no longer a serious problem.
179* ''ComicBook/TheMightyThor'' supporting character Beta Ray Bill is a cyborg whose body was built with [[PowerLimiter safeguards to prevent his internal reactor from overloading]]. By releasing these safeguards, he can multiply his power by many times. The drawback is that after a few minutes of this, his reactor will reach critical mass, with [[PowerIncontinence explosive consequences]].
180* {{Downplayed|Trope}} by Nightcrawler of the ''ComicBook/XMen''; he can carry someone else with him while using his mutant ability to teleport, but the strain is, in his words, "murderous", both to him and the passenger. Doing it more than once would likely kill them both. However, this lessens as he learns his powers better. The first time he did it, he screamed in agony and he and his passenger were incapacitated for some time. Now it's something he easily does, though it leaves the passenger disoriented. One of his favorite techniques is to grab an opponent and make several jumps, leaving his opponent to suffer while he remains unharmed, though he still must take care not to exhaust himself when doing this. A sufficiently tough opponent can be left unharmed while the strain of multiple jumps continues to add up and [[HoistByHisOwnPetard do him more harm than the enemy]]
181* ''ComicBook/{{Bamse}}'' has a child-friendly version in Nalle-Maja's reaction to dunderhonung ("thunder honey", a special kind of honey mixture). She is one of only two regulars for which it grants a period of super-strength, the other being her father, the eponymous Bamse. Unfortunately, once the strength fades she also gets what everyone other than Bamse (and her younger sister Brumma, who is completely unaffected by dunderhonung) gets when they consume dunderhonung: three days of horrible stomach-ache. As a result, going into her father's supply of dunderhonung is something she only does in an extreme emergency when they need someone with super-strength ''right now'' and Bamse isn't available.
182[[/folder]]
183
184[[folder:Fan Works]]
185* ''Fanfic/AGrowingAffection'' has a few:
186** Naruto's original technique, the Blood Clone Jutsu uses blood to form clones almost as tough as the creator, that return any leftover chakra to the original when the technique ends. But the amount of blood required means that anyone without a healing factor would pass out creating more than one Blood Clone. [[spoiler:Naruto creates a stronger version that has Sakura and Ino heal him and give him plasma pills so he can make a small army of blood clones.]]
187** Breaking the Souhi is not unlike the retributive strike below, it (according to lore anyway) instantly reduces the temperature of everything in a five-kilometer radius to -100 degrees (Fahrenheit or Centigrade not specified), including whoever breaks it.
188* ''[[https://archiveofourown.org/works/3814345 Breath Of Life]]'': In this ''WesternAnimation/AvatarTheLastAirbender'' fanfic, Aang reveals that the [[BlowYouAway Air Nomads]] had a bunch of dangerous techniques designed specifically to kill that were invented by rogue Airbenders. The [[MartialPacifist pacifistic]] Air Nomads considered these techniques dangerous because their deadliness went against their way of life and had the knowledge locked up. The reason Aang knew these techniques was because he was forced to learn them when the monks found out he was the Avatar.
189* ''Fanfic/ChildOfTheStorm'':
190** Wielding dark magic is this - even if you're capable of avoiding the corrupting effects, it has a price, even if you're as skilled and powerful as Albus Dumbledore, who had to delve into the very depths of the Dark Arts to defeat Grindelwald. He refuses to elaborate on just what that price was. And even sociopathic {{necromancer}} Gravemoss refuses to pay the price for unleashing some of the stuff in [[TomeOfEldritchLore the Darkhold]].
191** In the sequel, Harry using [[spoiler:his inner Phoenix fragment]] qualifies as this on several levels, mainly because it's insanely volatile. Unless you're incredibly careful, WithGreatPowerComesGreatInsanity, and you end up becoming [[spoiler:the Dark Phoenix]], as he does at the end of ''Forever Red''. Plus, there's the fact that it weakens the already very fragile fabric of reality and risks unleashing [[spoiler:Surtur, the original Dark Phoenix]].
192* ''Fanfic/DekiruTheFusionHero'':
193** Izuku views Human Fusion as this. While an incredibly powerful technique, it has many downsides. It's CastFromStamina, with even more stamina being drained when using taxing techniques/abilities like One for All, its MentalFusion aspect risks revealing personal information and secrets to all component partners, all injuries endured during the fusion will be split amongst every component partner, and it's ''very'' unpredictable, as the fusions are entirely his or her own person. Unless Izuku has merged with the component partner before, whichever Quirk the resulting fusion has will be completely unknown until he or she figures it out themselves. As a result, it's best used as a last resort. Aizawa actually praises him for this view, because it shows that he won't be a victim of CripplingOverspecialization, which can be fatal for a hero.
194** [[spoiler:Multi-person fusions. While they are more powerful (enough to rival ''All Might''), they drain even more stamina than the standard one-person fusion, especially from Izuku. Using a multi-person fusion more than once a day can cause potentially fatal exhaustion to him]].
195* ''WebVideo/DragonBallZAbridged'': Parodied when Nail suggests to Piccolo to fuse. Nail tells him that the technique is forbidden even amongst their highest clans... only for Piccolo to ask if they're just going to abuse it. "Maliciously!"
196* ''Fanfic/ADropOfPoison'': Naruto copies the whole scroll of kinjutsu. Some of them are just outright suicidal, but many others are quite useful in the hands of disposable shadow clones. For example, the Evident Hellfire technique allows the user to gather fire chakra in a ball, and just keep gathering it, potentially for weeks on end, so long as they can keep the ball stable. But it doesn't give feedback about how much chakra is inside, and when it bursts, it all goes up in one big bang.
197* ''Fanfic/GettingBackOnYourHooves'': Twilight mentions unicorns have more potential magical power than they can safely use, which operates on the same principle as muscles being capable of far more than they can safely use. Using their maximum power would drastically increase what they can do, but at the risk of damaging or breaking their horn. [[spoiler:At the finale, [[BigBad Checker Monarch]] does this after her EngineeredPublicConfession in an attempted TakingYouWithMe on Trixie and the mane cast. It not only fails but her horn is badly damaged as a result.]]
198* ''Fanfic/{{Hyphen}}'': The Ancestor's orb, implied to be [[spoiler:Shadow Gardevoirite]], contains some of the Ancestor Gardevoir's memories and knowledge, as well as great and terrible power. Astra's mother used it to fight a threat to the village, killing herself and Astra's father at the same time. It leaves behind an area of cold, lifeless desert where nothing will ever grow again. The first time Astra truly tries diving into the orb's power, [[spoiler:she's overcome by murderous hatred towards people she's been angry at and causes a massive wake of similar destruction in the forest and scarring the sky itself a putrid, bruising yellow]]. As soon as she comes back to her senses, she's horrified.
199* ''Fanfic/JusticeSocietyOfJapan'': Parodied in an omake, where [[Anime/DragonBallZ Mr. Satan]] and [[Franchise/StreetFighter Dan Hibiki]] both claim to know one of these, but are both too scared to actually perform it.
200* ''Fanfic/TheLegendOfCynderSeries'': Myst's fury, after she takes a potion to help cure her blindness. The potion has a side effect of drastically increasing a dragon's powers the more they drink; Myst needed to drink a whole bucket's worth to purge The General's poison that was blinding her out of her body. It's heavily implied that Myst's fury would be one of the single most powerful attacks in the entire fic series. However, it would have the unfortunate side effect of killing her if she were to release that much power at once. As such, she has never once used it so far.
201* ''Fanfic/MyHeroSchoolAdventureIsAllWrongAsExpected'': In both this fic and [[Manga/MyHeroAcademia the source material]], Tokoyami's Quirk, Dark Shadow, becomes incredibly powerful but also impossible to control in absolute darkness. However, this is {{Subverted|Trope}} with Hachiman's [[PowerCopying copied version]]. Thanks to starting at merely 1/108th the power of the original, pitch-black darkness instead just makes Dark Shadow strong enough to be usable even without [[VancianMagic prior Stockpiling]].
202* In ''Fanfic/{{Origins}}'', Dr. Kevin Filner comes up with one. In order to fight [[spoiler:the Flood]] the heroes need ships that don't have crews. Unfortunately, all the power sources that have been used for various warships so far are either inadequate or run on some form of {{Unobtainium}} like hypermatter. Consequently, he suggests using biotic batteries, like a certain [[HeelFaceTurn villain-turned-at-least-nonthreatening]] -- Sarah. He repeatedly lampshades how much trouble he will be in for suggesting such a thing, and considering these are [[MamaBear Jack's]] students we're talking about, he's probably right.
203* ''Fanfic/PokemonResetBloodlines'': [[LimitBreak Z-Moves]] can only be used once per day because they drain both the Pokémon and the trainer of a lot of energy. It's known that people have ''died'' trying to perform them consecutively within the span of ''hours''. [[spoiler:However, Bloodliners seem to be capable of using them consecutively without fatal risks in the span of minutes with different Pokémon, albeit not without [[PowerStrainBlackout collapsing after doing so]].]]
204* In ''Fanfic/{{Pokeumans}}'':
205** [[SpiritAdvisor Spiritus]] reveals to Brandon that as an Energy Channeller he may be able to perform Total Absorption - which would consume the enemy's aura (and by default, [[ThouShaltNotKill is totally fatal]]) and [[WithGreatPowerComesGreatInsanity may even take a hit on his sanity]] to the point of unleashing a SuperpoweredEvilSide.
206** Rikuto of the Long Island Elite Four apparently knows many of these but must restrain himself from using because, well, he can't kill all of the base's most promising battlers whenever they fight him.
207* ''Fanfic/QueenOfShadows'': The primary fighting technique employed by [[WarriorMonk Toguro]] uses chi to expand his strength and speed beyond human norms. However, Ikazuki notes that this has the side effect of [[CastFromHitPoints draining his life force in the process]].
208* ''Fanfic/RanmaSaotomeChiMaster'' has the Black Dragon Breath Technique, which greatly increases the amount of chi the user has at his or her disposal, and automatically channels it into a dragon-shaped battle aura around the user. The drawback is that it puts a ''lot'' of stress on the user's body. Since the battle aura is so compact, it eventually causes the user's muscles to tear themselves apart. Even worse, the breathing exercises required to maintain the aura starts rupturing the blood vessels in the lungs after a while, eventually causing the user to drown in his or her own blood.
209* ''[[https://archiveofourown.org/works/25178320/chapters/98212914 That Time I Got Thrown Across Dimensions and Landed On My Big Tiddy Redhead GF Who Is Also A Devil]]'': The second holder of One for All had a Quirk that massively boosted all his physical abilities until his body started tearing itself apart. All For One attempted to use his other Quirks to counter this disadvantage, only to find it boosted his Quirks just as much. He swore not to use it until a century after he stole it, when facing Izuku who was completely overpowering him. In a ShoutOut to ''Manga/{{Naruto}}'', All For One's body starts cooking from the inside as he uses it, eventually blackening and crumbling away to ash.
210* ''Fanfic/ThisBites'':
211** Not long after the events of [[Anime/OnePieceFilmStrongWorld Strong World]], Sanji created a culinary example. [[MedicinalCuisine The Death's Door Lunchbox]] is a meal that contains enough nutrients to feed an army of normal humans for seven days, which is enough to bring [[BigEater Luffy]] back from the brink of death. He explicitly warns Luffy not to eat it unless he was absolutely starving and needed excess energy, otherwise, the concentration of nutrients could kill him.
212** Chief Warden Magellan has a technique called ''Poison Goetia'', which involves manifesting [[BlobMonster animal shapes made of distilled venoms from his meals]] and then eating them in order to mix together every single possible poison in his system into a new ultimate attack, the ''Typhon Genesis''. His mental narration as he chows down makes it very clear that this move is pushing his body's resistance to poison to its limit, and could kill him.
213* ''Fanfic/TowerOfBabel'': Possession is forbidden in this ''VideoGame/NieR'' fanfic for this exact reason. It grants the Shades more power, but there is a high chance of [[WithGreatPowerComesGreatInsanity relapsing]], especially if the host fights back.
214* ''Fanfic/{{Transcendence}}'': Ichigo's [[SuperMode bankai]] effectively makes him a juggernaut that can go head-to-head with some of Azeroth's toughest entities. However, his vessel can't withstand the strain his power puts on it, so he can't use his bankai for more than a few minutes without risking it causing [[HeroicRROD heavy damage to his body]]. Even if he doesn't leave it active for long, deactivating it immediately leaves him exhausted. As a result, Ichigo treats bankai as a [[GodzillaThreshold last resort]].
215* ''Fanfic/TruthAndConsequences'': Wielding the Ladybug and Black Cat [[TransformationTrinket Miraculous]] [[YinYangBomb together]] is presented as this. In ''theory'', you can become a RealityWarper, capable of making your heart's desire come true. In ''practice'', it requires an incredibly strong will and perfect spiritual balance. Only one person has ever successfully pulled it off, with the consequences of the failures ranging from turning the wielder's hair orange, to transforming them into a potted plant, to [[RetGone Ret Goning]] an entire civilization. Marinette is convinced she can pull it off; everyone else, not so much. [[spoiler:When Gabriel gets his hands on both, not only does he [[CameBackWrong fail to resurrect Emily]] but he himself is seemingly annihilated - taking both Miraculous with him]].
216* ''Fanfic/TheUltimateEvil'':
217** It's rumored that if the Book of Ages is damaged, or if too many inconsistencies are made when its [[RealityWarpingIsNotAToy reality-warping power]] is put to use, the fabric of reality will be destroyed. In ''The Ultimate Evil'', [[spoiler:the former risk becomes a [[ApocalypseHow/ClassX4 reality]] when the Book gets burned]], though [[spoiler:Valerie and Shendu [[BigDamnHeroes fix it]] before it's too late]].
218** In ''The Stronger Evil'', Nataline fears this regarding the powers Valerie has gained [[YinYangBomb from bonding with Shendu]].
219** Jade taking on [[MarkOfTheBeast Tarakudo's mark]], the [[EvilIsNotAToy same as in canon]], in the first story. In the second story, she [[spoiler:takes on the mark despite knowing the dangers in an attempt to command the Shadowkhan to turn on Tarakudo. A pity she [[NiceJobBreakingItHero didn't count on]] Tarakudo [[RaceAgainstTheClock speeding up and forcing]] her transformation back into her SuperpoweredEvilSide]].
220* ''Fanfic/{{Vapors}}'': Subverted in this ''Manga/{{Naruto}}'' story, where the Hiraishin should be this given the numerous ways to TeleFrag yourself or worse. In fact, it has several safeguards built in to avert this, although using it [[spoiler:with cranial hemorrhaging]] is still a very bad idea.
221[[/folder]]
222
223[[folder:Films -- Live-Action]]
224* In ''Film/BladesOfGlory'', the Iron Lotus is a figure skating technique developed by the coach in his "wild youth", but only one country was crazy enough to try it -- North Korea. The only attempt resulted in [[OffWithHerHead the woman's head being cut off]] [[AbsurdlySharpBlade by the man's ice skate]] (as impossible as this sounds). According to the coach, the only way for the technique to be performed successfully is by a pair of two men.
225* Shows up early in ''Film/TheFastAndTheFurious2001'': Brian, in his first drag race, uses his nitrous too early and is in danger of losing the race. In desperation, he uses a second nitrous burst, still loses, and severely damages his engine as a result. No one in the entire series of movies ever uses nitrous twice, except for this one instance.
226* The titular skill in ''Film/FingerOfDoom'' is a powerful kung-fu magic which drains the ''life'' out of any human victims, turning them into lifeless, zombiefied husks of their former selves, but at a cost where the practitioner will become a vampire (or the equivalent of one, as they couldn't expose themselves to daylight). The villainess who learns this skill, despite being warned by her mentors not to beforehand, actually ''embraces'' herself becoming a vampire as she then goes on an indiscriminate killing spree across towns, with her zombie minions carrying her in a coffin during the day.
227* ''Film/Ghostbusters1984'': The Proton Packs fire a stream that can snag a ghost like a lasso. But the device is very unstable, and if the proton streams met, it would cause a "total protonic reversal", leading to all life coming to an end simultaneously and every molecule in the user's body exploding at the speed of light. [[spoiler:They're forced to use it to end Gozer's threat at the end of the first movie. Thankfully, all it does is cause a big boom and cover New York in marshmallow, because seemingly all the effects remained on the other side of the portal.]]
228* ''Film/GhostbustersAfterlife'': Confronted by [[spoiler:Gozer]] the [[spoiler:original Ghostbusters]] cross the streams. It doesn't work this time, as they're [[spoiler:one beam short]], and [[spoiler:Gozer]] uncrosses the streams.
229* In ''Film/HighlanderEndgame'', the unbeatable sword technique is unbeatable, if both duelists simultaneously block each other's weapons behind their heads as if locking them in place. Even with centuries of sword practice, the results of this technique cannot be avoided. The two combatants cannot simply disengage from combat, slowly making sure their swords are not aimed at each other's necks. It simply cannot happen.
230* In ''Film/{{Inception}}'', the "Mister Charles" routine is treated this way. It amounts to an InvestigatorImpersonation turning a target against their own subconscious, and Cobb's associates are afraid to let him use it. If it goes right it will help them out of a bind, but if it goes wrong it will be ''very'' bad, and Arthur implies this has happened to them in past jobs.
231** Cobb regards the titular concept of "Inception" this way; implanting a suggestion into a target's subconscious is incredibly useful, but to do so requires going three or four layers deep, when two is usually the maximum. Not to mention that the suggestion lingering in the target has dodgy moral implications.
232* In ''Film/{{Jumper}}'', the teleporting Jumpers can easily move themselves and another person, but greater masses are more difficult. Griffin is able to jump cars and a double-decker bus at one point, but only when they're moving and it's implied he's using their momentum to take some of the strain off; he also relates a tale of a Jumper who tried to teleport an entire building, noting that this Jumper only managed to shake it a little before the strain killed him. In the climax, [[spoiler:David manages to jump a sizable portion of his girlfriend Millie's apartment twice without killing himself when he was basically trapped in the apartment by his enemies, but it took a lot out of him]].
233* ''Film/KillBill'': The Five Point Palm Exploding Heart. It is the deadlieast fighting technique since it could [[spoiler:slowly-but-surely kill the victims without them realized it]] that [[ArrogantKungFuGuy Pai Mei]] refused to teach it to anyone (including Bill). That’s why, Bill is so surprised upon learning that the Bride is revealed to [[spoiler: be [[TheChosenOne the only one]] who inherits this top secret technique when using it to kill him]].
234* In ''Film/KissOfTheDragon'', Creator/JetLi describes the titular technique as "very secret, very forbidden". The technique actually poses no danger to the user; it is forbidden because of its effect on the target.
235* In ''Film/ManOfTaiChi'', Tiger's master's ultimate move qualifies due to its obscene killing power. When his master ''pulled'' the attack and didn't even make physical contact with Tiger, it still left severe bruising and caused BloodFromTheMouth.
236* ''Franchise/MarvelCinematicUniverse'': Some of Ant-Man's more elaborate abilities are treated this way:
237** In ''Film/AntMan1'', going beyond subatomic size can only be accomplished by disabling the suit's regulator, which means you aren't coming back once you do. [[spoiler:Scott finds a way to do it, though, albeit requiring a specific setup]].
238** ''Film/CaptainAmericaCivilWar'': [[spoiler:Scott turning to giant size]].
239--->'''Ant-Man:''' On my signal, run like hell. And if I tear myself in half, don't come back for me.\
240'''Captain America:''' You sure about this, Scott?\
241'''Ant-Man:''' I do it all the time! I mean, once. In a lab. And I passed out.
242** ''Film/AntManAndTheWasp'' exploits and explains both of the above: safe "bridges" to the subatomic world only appear once in a century, and Hank Pym has to develop a whole new machine to properly shrink (and later return) in a ship [[spoiler:so he can go there in search for his disappeared wife]]; and the taller you grow, the less you can keep yourself conscious, given [[SurprisinglyRealisticOutcome the human body will pass out due to the extra weight and increased oxygen intake]].
243** ''Film/DoctorStrangeInTheMultiverseOfMadness'': The "Dreamwalker" ritual is said to be the most dangerous spell in the [[TomeOfEldritchLore Darkhold]]. The ritual allows the user to project their consciousness into the mind of a version of themself in an AlternateUniverse, fully taking control of that person's mind and actions for the duration of the spell. Extended usage places both universes at risk of complete destruction.
244* In ''Film/OverdrawnAtTheMemoryBank'', Apollonia watches a film on Identicube/Computer Interfacing when it becomes clear that they need to save Aram Fingle when his body is misplaced. It's this trope as it is highly possible that both the person in the Identicube and the person connected to the computer could end up losing their minds, becoming vegetables.
245* The Poison Fingers from ''Film/ThePaperTigers'' is a gung fu move that, with a few taps on the back, can cause a TimeDelayedDeath indistinguishable from a heart attack.
246* In ''Shall We Dance'' 1996 and 2004, this trope is applied to a dangerous maneuver in ballroom dancing.
247* The entire point of TheDarkSide in ''Franchise/StarWars''. The lure of easy power [[PowerAtAPrice comes at the price]] of becoming DrunkOnTheDarkSide. [[AllThereInTheManual The Expanded Universe]] defines the deadliest lightsaber style as Juyo/Vaapad, a mainly Sith technique which is [[AxCrazy extremely aggressive]]. For that reason, it's forbidden to most Jedi except those who demonstrate they're capable of handling it safely -- ''i.e.'', without slipping to the Dark Side. Mace Windu is the creator and supreme master of Vaapad.
248** ''Film/TheLastJedi'' reveals that AstralProjection is one such technique for all Force users. As Kylo Ren notes, it's an extremely powerful ability, but the physical strain it causes (especially if done over large distances) is so tremendous that it will likely kill the user. In the climax, [[spoiler:Luke uses it to distract the First Order and ensure the Resistance escapes; sure enough, the strain of projecting himself across several light-years for an extended period of time kills him, causing him to [[AscendToAHigherPlaneOfExistence become one with the Force]].]]
249** ''Film/TheRiseOfSkywalker'' introduces a technique called "lightspeed skipping", a series of brief jumps that Poe uses to pull a HyperspeedEscape from the First Order. It works, but the Millennium Falcon is on fire when she returns to the Resistance base.
250[[/folder]]
251
252[[folder:Literature]]
253* Although not illegal, a gunsmith in Stephen Hunt's ''The Court Of The Air'' warns Oliver that multi-shot firearms are called "suicide guns" for good reason in their world: bullets are made of glass and explosive tree sap, not metal and gunpowder, so loading more than one round at a time poses a very high risk that the shock wave from your first shot will rupture your second bullet's sap-chambers and make the weapon blow up in your hands. [[spoiler:In the concluding battle, the Court wolftakers reveal that they've licked this problem by cushioning individual cartridges against such shocks and thus, developed glass-bullet ''machine guns'' fed by rubber ammo-belts.]]
254* ''Literature/CradleSeries'': The Blackflame Path, a sacred art stolen from dragons, which was used to build an empire. In a world where AsskickingLeadsToLeadership and everyone challenges everyone, ''no one'' challenges the Blackflame sacred artists. Not only is it [[CripplingOverspecialization focused on offense to an insane degree]], but the flames are not designed for humans; they slowly eat away at mind and body, resulting in the imperial family slowly dying out without any outside intervention at all. [[spoiler:When Eithan admits that he plans to train Lindon in this path, Cassias starts ''screaming'']].
255* Death magic in Creator/LoisMcMasterBujold's ''Literature/TheCurseOfChalion'' causes both the target and the caster to die as their souls are borne off to the Bastard's Hell (when it works at all). Luckily for some so affected, not only is the Bastard's Hell more of AHellOfATime than a FireAndBrimstoneHell, but they don't always stay there, as some of the other gods may take them up. This also means while unsuccessful attempts or research are regarded as attempted murder (at least) and dealt with by temporal authorities as such, ''successful'' attempts are not prosecutable -- not only because there's nobody left to prosecute, but also because if it works, it's considered divine intervention.
256* In ''Literature/DevilVenerableAlsoWantsToKnow'', the [[BloodMagic Blood Severing Art]] is a cultivation technique that brings a person's body and soul to the brink of death and then fuses them together to give them unimaginable power and immortality as long as a single drop of their blood remains but it's so dangerous that only one person in all of recorded history successfully did it ten thousand years ago and they got corrupted into a demon addicted to consuming other cultivators' souls who the entire rest of the cultivation world had to band together to stop them from killing everyone.
257* The ''Literature/{{Dragaera}}'' series has "Elder Sorcery", which involves the direct manipulation of raw chaos, and the practice of which is a capital crime by imperial edict. Those who research and practice it do so mainly out of curiosity or the search for knowledge, since elder sorcery has long since been supplanted by the ''much'' safer and easier use "normal" sorcery, where the energy of raw chaos is first filtered through the Imperial Orb before being used. However, there are some circumstances where normal sorcery doesn't work, forcing the characters to resort to elder sorcery.
258* ''Literature/TheDresdenFiles'':
259** A wizard's death curse. Put simply, the wizard, knowing they are about to die, draws up all their power and unleashes it in an extremely powerful spell, usually a curse on whoever was killing them. This leaves no energy to keep the brain or heart working, so the wizard dies immediately on casting.
260** Hellfire, which is demonic power that enhances spells but is only available when your soul is corrupted by a Fallen Angel. Soulfire, Hellfire's divine counterpart, uses the stuff that comprises your ''soul'' as the power source. Use too much Soulfire without giving yourself time to recover and your soul literally evaporates into your spells, killing you (and maybe then some). It's not so much forbidden as simply not available to most people have access to, however.
261** Any sort of Black Magic qualifies for human wizards and practitioners, as every time you break one of the Seven Laws, you corrupt your own psyche enough that breaking them again seems easier and easier to justify. Prolonged usage can progressively turn even the best-intentioned Black Magic user into a gibbering psycho. Plus, the White Council is ''very'' likely to cut your head off if they find out what you've done -- it's their experience that ''not'' turning into a mass-murdering BigBad after you perform one of these seven acts is rare enough to make getting out the ax before you can get started their first resort. The Council has one enforcer, known as the Blackstaff, whose namesake weapon insulates his mind from the effects and is thus free to perform any magic he sees fit in the line of duty.
262** Casting spells inside a ring of fire, is forbidden for anyone affiliated with the White Council who is not a Warden. Doing so isn't considered black magic, but it amplifies the power of any spell cast to dangerous levels, as well as the effects of any mistakes made during the casting, making doing so extremely dangerous.
263* ''Literature/DungeonCoreChatRoom'': [[spoiler:The gods designed the system of levelling up to replace cultivation with something easier, safer, and universally accessible. However, cultivation did theoretically allow for faster growth,]] at the cost of risking madness, mutation, PowerIncontinence, or sudden death from a lack of self-control. It's still possible to use demonic mana to disconnect from the [System] and potentially grow stronger, but not only does it have the aforementioned drawbacks, it also requires HeroicWillpower to avoid DemonicPossession.
264* In ''Literature/FateZero'', Kiritsugu Emiya can use the "Innate Time Control" magecraft to internally affect time -- speed it up for superhuman reaction time in combat, or slow down his bodily functions to avoid a search-and-destroy system. Bad thing, once Kiritsugu stops using it and his body automatically re-synchs with the rest of the world, he can suffer ''very'' ugly internal injuries. [[spoiler:Only by using Avalon, the scabbard of Saber's sword which grants its bearer regeneration, can Kiritsugu go beyond Double Accel with Time Alter, allowing him to use Triple and Square Accel, and even slow his biological processes down to a third of their normal speed this way]].
265* In Creator/LarryCorreia's ''Literature/TheGrimnoirChronicles'', Actives who draw hard enough on their power die. Most who do during the course of the trilogy were already mortally wounded. None of them survive.
266* German author Hans-Hellmut Kirsch, in one of his "Gunner Asch" novels set in [=WW2=], fictionalises an actual incident where a young anti-aircraft gunner skips several steps in the taught loading and firing drill, simply to get more shells in the air among the attacking American bombers. This works fine and his crew manages to double their firing rate. Until the semi-automatic breach of a heavy flak gun pulls in, and then slams shut on, the gunner's right arm. The rest of the crew then realise this is why the drill was evolved this way - to load the shell, and not somebody's arm well past the elbow.
267* From the ''Literature/HarryPotter'' series:
268** A set of three spells is known as the "Unforgivable Curses"; their use lands an automatic life sentence in Azkaban. This is mostly due to their power; one is essentially a MindControlDevice, one is an AgonyBeam, and one just [[OneHitKill kills]]. It's almost impossible to use them without really, truly wanting the consequences (when they are introduced, the teacher explaining them claims that the entire classroom of fourteen-year-olds he's talking to could pull out their wands and try to use the killing curse on him ''en masse'', and he doubts he would get as much as a nosebleed, and when [[spoiler:Harry]] later attempts to use [[AgonyBeam the Cruciatus Curse]] [[spoiler:when overcome by anger and grief over Sirius Black's death]], the person he uses it on is merely knocked off their feet and explains that using the Cruciatus curse requires actually and genuinely wanting to sadistically torture someone and that righteous anger won't work), meaning that their use proves the user's malice. The only general exception is in dealing with wizarding terrorists on the scale of the Death Eaters, who are essentially outlaws due to how dangerous they are (the only known specific outlying exception involving [[spoiler:assisted suicide]]).
269** The use of [[SoulJar Horcruxes]] is so forbidden that it's hard to find any information on how to make one because it involves fracturing the soul, and doing ''that'' involves murdering people. Even the author of a book on Dark Magic titled ''Magick Most Evile'' [[EvenEvilHasStandards refused to elaborate]] even slightly on the process.
270** The drinking of unicorn's blood grants one life, even when one is all but dead, but at a terrible cost: that one lives a half-life, a cursed life, from the moment the blood touches their lips.
271** Fiendfyre is an incredibly powerful fire spell capable of destroying even Horcruxes, but it is also extremely difficult to control. When Crabbe used it against Harry and his friends, the only person he killed with it was himself and the soul fragment in the Horcrux.
272* Creator/MercedesLackey's ''Literature/HeraldsOfValdemar'' has the "Final Strike", in which a mage uses up all his energy in an offensive spell, thus killing himself along with whatever is aimed at. It works, too, in the [[DownerEnding tragic]] ending of the ''Last Herald Mage'' trilogy. Elsewhere in ''Valdemar'', [[spoiler:Vanyel's already massive power results in a Final Strike that is so literally earth-shaking that the geography of northern Valdemar is forever altered]], and in the ''Owl Knight'' trilogy [[spoiler:poor old almost-powerless Wizard Justyn must expend his Final Strike to destroy the single bridge that stands between a marauding barbarian tribe and his fleeing village]].
273* ''Literature/HighSchoolDXD'' gives us Juggernaut Drive, which allows the users of [[EmpathicWeapon Boosted Gear or Divine Dividing]] to completely unseal the Dragon contained within, transforming into a near-unstoppable, monstrous form that goes on a berserker rampage until the user's life is consumed. Both [[TheHero Issei]] and [[TheRival Vali]] have to find a way around this. [[spoiler:Vali has, long before the start of the series -- as a BornWinner, he has a ''stupid'' amount of Devil-power and fuels his JD with that instead of his lifeforce. Issei forgoes the form entirely in favor of creating Cardinal Crimson Promotion, an exhausting but near-equal power boost that relies on his link to Rias, befitting his role as TheChampion.]]
274* In ''Literature/TheIrregularAtMagicHighSchool'', there is a species of alien worm ("parasites") that [[BrainwashedAndCrazy overtakes a host's mind]] to puppet the physical body it leaves behind. People of sufficiently strong will can ''prevent'' a parasite latching onto them in the first place, but there is absolutely no way of reclaiming someone once a parasite has started to burrow. Still, [[spoiler:Minoru]] is frustrated enough by his chronic health conditions that he consciously lets a parasite into his mind [[BattleInTheCenterOfTheMind and fights it for control there]], hoping to use its power to fix himself. This ''works'' (or seems to; [[MoreThanMindControl the nature of parasites]] means that he wouldn't know if he had been overtaken), giving him all the benefits of a parasite connection and none of the downsides. Even so, [[spoiler:Minoru]] must live the rest of his life exiled on a spaceship, because someone willing to take a risk like that- knowing how many people an ''un''controlled parasite would try to kill- cannot be trusted to live among the general population.
275* ''Literature/JourneyToChaos'': Videlct Mens greatly amplifies the might of warriors and mages but overuse of it can kill them or drive them insane. This is why Tiza has to obey a number of rules set by mentor when using it. They boil down to "Don't use it unless you've passed the GodzillaThreshold".
276* [[LanguageOfMagic The Cants]] in ''Literature/KnightsOfTheBorrowedDark'' are a dangerous technique already, carrying a [[PowerAtAPrice Cost]] of slowly turning the wielder's body to iron. The Knights avoid using them if at all possible, relying on [[MagicKnight traditional weapons]] with their powers as a last resort. The Higher Cants are even worse, taking a heavy toll on the body and hastening the Cost severely - when Denizen tries to copy Grey's use of Sunrise and screws it up, the shock almost kills him and he loses most of his hand to the iron.
277* Shapeshifting into another person in ''Literature/TheLicaniusTrilogy'' is excruciatingly painful and difficult. It also requires that you personally kill the individual you plan to impersonate.
278* In ''Literature/TheMagiciansNephew'', the {{Prequel}} to Literature/TheLionTheWitchAndTheWardrobe, there is a dark spell called the Deplorable Word. When it is spoken, every form of life in the world with the sole exception of the speaker is killed instantly. [[BigBad Jadis]] boasts about the extensive measures she took to learn this and then use it to kill everybody in her homeworld as part of her backstory. [[UsefulNotes/WorldWarII Considering the time Lewis wrote it,]] it's quite blatant [[AtomicHate what it's supposed to symbolize.]]
279* ''Literature/MusketeerSpace'' has pilot drugs, which increase a pilot's connection to their spaceship and boost their flying skills by a good margin, with the tradeoff that their nervous systems are so wired into the ship that any damage rebounds directly into the pilot's brain. They're illegal for everything except very early training with an experienced copilot, and outside the law are mostly used in dangerous virtual-reality Duels. [[spoiler:It's revealed [[BrokenAce Athos]] habitually uses nexus, one of the strongest drugs, while flying to mitigate the effects of his alcoholism, which nearly kills him when he and Dana get into a pursuit battle.]]
280* In Creator/GarthNix's ''Literature/OldKingdom'' series, the last of the bells of the necromancer throws everyone that hears it deep into Death, including whoever rings it. There is nevertheless a point in the series where the situation is desperate enough for this to seem like a good idea.
281* In ''Literature/{{Pact}}'', summoning a demon is actually spectacularly easy -- all you need to do is state their name a certain number of times, and they will come. Of course, there's nothing preventing said demon from immediately inflicting a FateWorseThanDeath upon you if you don't take extensive precautions, and even if ''you'' are protected, a demon is defined by its pure hatred for existence itself, and summoning one will diminish the world as a whole--candles get a little less bright, gasoline lasts a little less long, and people are a little bit worse to one another. [[CrapsackWorld There's no known way of reclaiming what the demons have already taken from the world]]. In some cases, [[RetGone there's no way of knowing what was taken]].
282* ''Literature/ThePendragonAdventure'': It turns out that [[spoiler:all Travelers can warp reality like [[BigBad Saint Dane]] can, but doing so drains the life force of [[{{Heaven}} Solara]]. Saint Dane avoids these drawbacks by relying on a warped version of Solara based on darkness.]]
283* In ''Literature/PerdidoStreetStation'', Isaac relates to Yagharek how a previous administration's Torque experiments were banned once pictures of what that utterly malignant energy had done to a rival city went public.
284* Overexert your magic in the world of ''Literature/RiversOfLondon'', and you're liable to give yourself a stroke or cerebral aneurysm. Some specific magical effects also have direct harmful effects, such as the face-warping spell that Punch uses on his possession-victims that [[spoiler:made Lesley's face ''fall off'' when it lapsed]].
285* ''Literature/TheRisingOfTheShieldHero'': The Curse Series is quite powerful, although it requires an adequate sacrifice in using its power as its name implies. The most notable attack is Naofumi's [[CastFromHitPoints Blood Sacrifice]] that absolutely '''ensures''' it utterly destroys an enemy, if not bring them to near-death. Unfortunately, as the name of the attack also implies, it expels blood from multiple areas on the user's body in order to act as the "payment" required for using said skill as it acts as the medium to use said skill, and if the user is not treated immediately after, he/she will most likely die and if they survive then he/she will be inflicted with a temporary curse that sharply debuffs his/her stats.
286* In the ''Literature/SchooledInMagic'' series, those who perform the necromantic ritual on another person receive vast power which corrupts their mind and destroys their humanity. It is a temptation for many who desire the power, but it is strictly forbidden by all and for all. In this series, fully 2/3rds of the known world is controlled by insane necromancers whom the rest of the world is at war with.
287* In Creator/PoulAnderson's "The Sensitive Man", the main character's abilities, which lead many to speculate that he's an alien, a mutant, or genetically engineered, prove to be CharlesAtlasSuperpower in the end. He explains how many are found in humans -- mostly psychotics -- and he's learned to draw on them. And since there are good reasons why normal humans can't normally do them, he's about to have a nervous breakdown because of the prolonged usage.
288* In ''Literature/{{Slayers}}'', Lina's Giga Slave is the mother of all Dangerous Forbidden Techniques. It consists of [[spoiler:summoning a fragment of the [[{{God}} Lord of Nightmares]] into the physical plane]], so not only will she die if it is miscast, but she'll take the entire universe with her. [[spoiler:Naturally, it's miscast, and only a literal DeusExMachina on the part of the Lord of Nightmares saves the day.]] Ragna Blade also consumes magic quickly enough to put the caster's life in danger if they try to maintain it for too long.
289* ''Literature/SweetAndBitterMagic'': Dark magic, as a result of drawing power from the earth itself, rather than [[CastFromHitPoints the witch]] or a source. The earth is imbalanced through doing this, and the effects are terrible. Naturally, it's outlawed and punishable to use.
290* ''Literature/TreeOfAeons'': Void mana is the most primal and powerful type of mana, and is capable of creating portals to other worlds. The princess of Baroosh gets her hands on restricted literature, and attempts to use void mana to summon more heroes into the world -- but rather than succeed, she merely inflicts massive damage on her own soul-spring. Even after being healed, she suffers long-term complications like void-induced nightmares. It later becomes apparent that successfully using void mana, unless you're innately able to manipulate it like the Zaratans, requires repeated exposure and healing until your entire soul-spring is changed into void mana -- not something that everyone can, should, or wants to undertake. Oh, and void mana also has a tendency to erase your existing levels and skills, so by the time you're a proper void mage, you'll almost certainly have lost every other class you might have held. Definitely not something to dabble in.
291* In ''Literature/UnlimitedFafnir'', Yuu is able to obtain tremendous power from an ancient dragon calling itself "Yggdrasil" in order to defeat dragons attacking humanity. Unfortunately it requires his memories in order to summon said powers.
292* In the first ''Literature/WearingTheCape'' book, Atlas warns Astra against just ramming into her target like a missile. It'll probably work, but (as he points out) you don't reuse missiles. Near the end of the book, Astra uses that exact technique against Seif-Al-Dein. It kills him, but the impact very nearly kills her as well.
293* ''Literature/TheWheelOfTime'':
294** The use of "balefire" is forbidden by the magic users of the world, and when people use it anyway, they're exceedingly careful with it. Balefire doesn't just obliterate its target, it [[RetGone goes back in time]] to do so, with all the potential paradoxes that implies. Entire cities and their recent histories disappeared from the face of the earth before the mages, good ''and'' evil, decided that maybe gratuitous use of balefire wasn't such a good idea. When Rand begins using it for more than a minute, it is seen as a sign of his rapidly deteriorating mental state impacting his judgment, though he is technically correct that balefire is the only way to ensure enemies such as the Forsaken are not resurrected by the Dark One.
295*** In the last book of the series, so much Balefire has been used the world itself starts falling apart, with cracks in the ground leading to nothingness.
296** Picking apart a weave of the One Power rather than leaving it to dissipate is a Dangerous Forbidden Technique among the Aes Sedai, and just a bloody dangerous technique among the Aiel Wise Ones. If executed perfectly, it won't leave a telltale "residue", which normally lets one channeler see exactly what another has done, but failure is extremely easy and can produce a range of consequences, including a lasting "fallout" effect that makes it difficult to cast spells in the entire region for a year or more. [[spoiler:When Elayne tries and fails, it produces a burst of wind. A burst of wind with the force of a small nuclear explosion.]]
297* In the ''Literature/WordBearers'' novel ''Dark Apostle'', creative thinking is viewed like this by the Mechanicus. Dangerous enough to be sealed away in a separate brain.
298* Creator/JinYong, who writes {{Wuxia}} novels, loves this trope, but none are more (in)famous than the Sunflower Manual/Bixie Swordplay Technique (featured in ''The Smiling, Proud Warrior''), which requires its male adherents to [[spoiler:[[CripplingCastration castrate themselves]]]] and slowly makes the practitioner more and more feminized.
299[[/folder]]
300
301[[folder:Live-Action TV]]
302* One episode of ''Series/{{Angel}}'' reveals that if a vampire has their heart surgically removed, they're unkillable for a certain amount of time but eventually die. The episode focused on a vampire DrivenToSuicide after [[VampireDetective Angel]] killed [[EvenEvilHasLovedOnes his girlfriend]], who got the surgery in the hope of [[TakingYouWithMe taking Angel with him]].
303* The bonehead maneuver in ''Series/BabylonFive'': Opening a jump gate within an existing jump gate, resulting in a massive explosion of energy that the ship who triggered it is highly unlikely to survive or outrun. The heroes only use it because it was the only way they could think of to shake the Shadow ship trying to kill them. Doubly dangerous, as this destroys the jump gate, leaving the system inaccessible to non-jump drive equipped ships until a (very rare) construction ship drops by to rebuild the jump gate. On this occasion the planet was already deserted, and the heroes had the additional motive of rendering it inaccessible to grave robbers.
304** Sometimes, a deathbed scan is the only way to get critical information. However, telepaths don't like doing them since many describe the experience as having part of them go with the departed. Those that have done four or five are described as being dead inside. Bester has gone on record doing ''eight''.
305* Resurrection spells in ''Series/BuffyTheVampireSlayer''. They either turn the dead person into a zombie or make them come back wrong and all screwed up.
306** And of course, the [[AllYourPowersCombined enjoining spell]] that the Scoobies use to defeat Adam. Giles' knowledge, Willow's magical strength, and Xander's [[TheHeart heart]], all combined with Buffy's super strength and resilience into one nigh-invincible Slayer, complete with {{Voice Of The Legion}} and [[GlowingEyesOfDoom Golden Eyes Of Doom]]? Cool. Being stalked and almost killed by the First Slayer [[YourMindMakesItReal in your dreams]] afterwards because the spell disturbed her spirit? Less cool.
307* L's fiddling with the ''Manga/DeathNote'' rules in the live-action movies could be considered this. There's also the more common in the anime world "technique" of Shinigami intentionally lengthening lives at the cost of their own.
308* Used ''on'' the main character in ''Series/EliStone''. When Eli needs to see the future with more clarity, he asks his acupuncturist Dr. Chen to use a little-known needle combination known as "The Dark Truth." After doing it once, Eli nearly has a heart attack, which makes Chen swear it off. So Eli winds up going to Chen's DistaffCounterpart and rival. He actually has the procedure done at least three times, which is probably why [[spoiler:his aneurysm gets worse by the end of Season 2]].
309* In ''Series/GameOfThrones'':
310** In a rather borderline case, Stannis uses this via Melisandre's [[spoiler:[[LivingShadow shadow assassin]]]] which [[CastFromHitPoints consumes his own energy]]. After using it, Stannis is [[RapidAging noticeably aged]] and Melisandre refuses to do it again because it could kill him.
311** Daenerys lets Mirri Maz Duur [[spoiler:cast a dangerous spell to keep Khal Drogo alive]]. It [[GoneHorriblyRight goes horribly right]].
312** We learn why exactly warging in humans is strictly forbidden among the wildlings. [[spoiler:There is a reason why Hodor can only speak 'Hodor'...]]
313** There is an experimental treatment for the fatal skin disease greyscale that has been forbidden for the risk it carries both for the maester administering it (since one slip up could get themselves infected) and the patient (since the cure is basically being ''skinned alive'').
314* The ''Franchise/KamenRider'' franchise has many modes that are dangerous to the user. Whether or not it lives up to the danger varies, from "one use kills major characters" down to "I thought it was forbidden but he uses it just fine over and over." In order:
315** ''Series/KamenRiderStronger:'' Yes, it's OlderThanTheyThink: long before form changing became the norm, the first Rider to do it has Charge Up, generated by a device implanted Shigeru's body. If he doesn't disperse the extra power in one minute, it will explode, blowing him to very small smithereens. Needless to say, he's never failed to finish the fight and execute his FinishingMove within the time limit. Meanwhile, Tackle has the powerful Ultra Cyclone attack. [[spoiler:Using it while already dying from poison finished her off]].
316** ''Series/KamenRider555:'' The Rider Gears run on Orphenoch DNA. The members of the Ryusei School were experimented on, the villains attempting to make new Orphenochs, so they can all activate it, but full compatibility isn't guaranteed. The Kaixa Gear's side effect: enjoy ''turning to dust'' once you de-transform or after a certain amount of time has passed. One use, you die, period. The Delta Gear's side effect is addiction, making you go AxCrazy in pursuit of getting to use it again at any cost. In both cases, ''transforming at all'' is the forbidden technique until they finally find their way into the hands of their main, compatible users. (Even then, using the Kaixa Gear starts to take a little more out of a Kusaka every time, with characters warning him not to use it.)
317** ''Series/KamenRiderBlade:'' King Form causes Kazuma to pass out the first few times he uses it. However, even once he gets the hang of it, the problem is that it slowly turns you into an Undead, one of the monsters of the series.
318** ''Series/KamenRiderKiva:'' The Dark Kiva armor is typically used by the BigBad and would prove lethal to any human who tries. A major character has no choice to use it to battle his even-stronger monster form, at the cost of his life.
319** ''Series/KamenRiderDouble:'' Twin Maximum, in which Double activates two [[FinishingMove Maximum Drives]] at the same time, temporarily taking his power up to 200%. Each of his battle modes is powered by two [[TransformationTrinket Gaia Memories]]. You activate the FinishingMove by placing ''one'' of them in that mode's weapon (for weapon finishers) or the side slot on the belt (for physical finishers.) Doing both at once is NOT recommended, as demonstrated when [[spoiler:Shotaro impulsively uses it in one battle, which lights him on fire and severely injures him]]. In the final battle of the series, [[spoiler:Double's SuperMode is powerful enough that he can combine the Xtreme and Prism Memories' Maximum Drives without ill effect]]. Also, the Fang Memory drives the user dangerously feral, but Philip was able to get control of it in one episode.
320** ''Series/KamenRiderOOO:'' This time, the suit changes in thirds! Three of a kind gets you a SetBonus, but side effects may include injury and insanity. The SuperMode comes with an even bigger risk: much like Blade King, OOO Putotyra takes the user one step closer to becoming more like the monsters whose essence powers it. Also, its first few uses make it so uncontrollable that Eiji has lost the ability to tell friend from foe and attacked his teammates. Unfortunately, it has the tendency to activate on its own...
321** ''Series/KamenRiderGaim:'' A character who has made a FaceHeelTurn and gone off the deep end is given a SuperMode capable of keeping up with that of the hero. The problem is, it drains the life of the user, and the inventor told him point-blank that using it would probably kill him. (In practice, its power level turns out to be as advertised, but whenever it sucks more energy from the user, the user is wracked with enough pain to barely able to stand, let alone fight. If not for the fact that the hero didn't want to harm him, using it would probably get him killed by an opponent, even a weaker one, before the life drain became fatal.) Oh, ''and'' the hero's super mode makes him more like the monsters, but this doesn't seem to come with any lack of control or turning into a monstrous form like in OOO.
322** ''Series/KamenRiderExAid:'' If you haven't had the compatibility surgery, trying use a Gamer Driver at all will wreak havoc on your body. Meanwhile, Proto Gashats (basically, the SuperPrototype of the TransformationTrinket, comes with powers the main ones don't have) harm the user a little more each time; "fortunately," the BigBad creates a SuperMode that lacks the side effect and heals him from his past uses of his normal mode. Also, Drago Knight Hunter Z is an emergency weapon for when the risk of going berserk is [[GodzillaThreshold not as bad as whatever is already going on]]. However, the secret to controlling it is that it's based on a four-player co-op game; each of the Riders is supposed to wear ''part'' of the armor.
323** ''Series/KamenRiderBuild:'' The Blizzard Knuckle amps up your attacks with [[AnIcePerson ice power]]. It can be used to transform if you don't mind dying. Also, there's an upgrade that can be applied to any hero or villain using the Hazard Trigger that increases your strength at the cost of dying if you ''are'' defeated in your new form. Major characters have been lost to both of these. Speaking of the Hazard Trigger, its "makes the user go insane" factor is no joke. It takes full control of Sento and drives him to kill with its ''first use.'' The other insanity-inducing power-ups, including this very series' Sclash Driver, are something that never drives the user as nuts as originally expected and is controllable in the end, but Hazard ''will'' turn you into a merciless killer, took a life in its ''debut episode,'' and remains a weapon of last resort for a long time. (Eventually, new armor that can control it is created.)
324*** To further elaborate on the danger of Hazard Trigger, it gets more power out of the [[StrongAsTheyNeedToBe emotion-based]] Rider system by overstimulating the user's brain, which inevitably ends in a state of [[LossOfIdentity mindless]] rage in a matter of minutes.
325** ''Series/KamenRiderZiO:'' The good news: Geiz Revive is a supermode supposedly able to handle anything up to and including Zi-O's evil future self, the dreaded Oma Zi-O. The bad news: it warps time and space to counter Zi-O's own space-time abilities, and the human body cannot long withstand being at the epicenter of that. If he uses it too often, it will endanger his life. At one point, another character was able to [[BatmanGambit successfully stop]] him by taking a CurbStompBattle from Geiz Revive... which left Geiz unable to fight for some time. Eventually this begins to affect him less, suggesting that the user's body simply takes time to become accustomed to it.
326** ''Series/KamenRiderZeroOne:'' Another uncontrollable mode, Metal Cluster Hopper is connected to the Ark, the evil satellite AI that is the series' BigBad and when it's forced on the hero, his other forms won't work! Rather than upping his anger or anything, it simply makes him a puppet of the Ark, [[NightmareFuel struggling uselessly as his body acts on its own]]. Eventually it is disconnected from the Ark, allowing him to safely use it on his own.
327** ''Series/KamenRiderSaber:'' The very next series follows it up with Primitive Dragon. Not only does it drive the user into a feral state that has him attacking everything in his path like a rabid animal, it ''also'' has a bad habit of activating itself like OOO [=PuToTyra=].
328* ''Series/LALaw'' has a sexual technique known as "The Venus Butterfly". An accused bigamist says that it is his key to success with women who would otherwise be out of his league and teaches it to his lawyer very reluctantly as he has always believed it had the potential to sexually enslave women.
329* In ''{{Series/Merlin|2008}}'', using the Cup of Life to become immortal. The result is that the person who drinks from it becomes the living dead of a sort, not a zombie, but tainted still.
330** On a lesser example, magic could be used as part of a ritual to save someone who was mortally wounded, or even allow a barren woman to conceive a child, but this required another life to be sacrificed to sustain the life that was being saved.
331* ''Series/OnceUponATime'' has a couple:
332** The Dark Curse (the spell which kicks off the events of the series) is one of only a few reliable ways of traveling between worlds. However, even most of the villains in the Enchanted Forest are too afraid to use it since activating it requires killing the person you love the most. Regina's desire for revenge on Snow White pushes her to the point of using the spell in the flashbacks of the first couple episodes. This is something of a variant because, rather than being dangerous for the user, it's dangerous for those around them; however, it may still count as Maleficent implies that the actions necessarily will result in permanent psychological damage.
333** There's also [[spoiler:the time spell Zelina creates in the Season 3 finale. Magic users in Oz discovered the secret to traveling through time but repressed the knowledge because of how dangerous it was (when Emma and Hook inadvertently use it, they nearly pull a [[Film/BackToTheFuture1 Marty McFly]] and prevent Snow and Charming from meeting; this could have caused Emma, and quite possibly all of Storybrooke, to cease to exist had they not rectified the situation). Like her sister, Zelina's desire for revenge pushed her to take such action.]]
334* In ''Franchise/PowerRangers'', morphing without [[Series/MightyMorphinPowerRangers a Power Coin]] is considered this. When Kat steals Kimberly's Crane Power Coin, Kim is forced to morph using the energies of the other Rangers until they're able to get the Power Coin back, causing drain to the entire team, Kimberly the most. Later, Adam ran the risk of killing himself when he morphed using the damaged Mastodon coin, though [[Series/PowerRangersOperationOverdrive Sentinel Knight fixed this later on.]]
335** There's also drawing power from the same source. The [[MemeticMutation "Too much Pink Energy is dangerous!"]] meme comes from this as there's no idea what may happen if two people use powers from the same source at the same time. It wouldn't be until ''Series/PowerRangersDinoThunder'' that we see what happens: two White Rangers, Trent and his clone, both suffer from shocks and power failures as a result of the Morphin Grid being unable to handle two copies of the same powers simultaneously. In ''Series/PowerRangersMegaforce'', the Ranger Changes the Super Megaforce team goes through is only temporary while in ''Film/MightyMorphinPowerRangersOnceAndAlways'', Rocky and Kat are willing to use the Proxy Power Coins despite the danger to save their friends and stop Robo-Rita.
336** ''Series/PowerRangersInSpace:'' Andros was unwilling to use the Red Battlized Ranger mode for this precise reason. The transformation hurts. He only uses it the first time because a little girl activates it for him.
337** Series/PowerRangersBeastMorphers features [[SuperMode Fury Mode]], a battlizer for the Red Ranger. It’s powered by Fury Cells, which have the negative effect of increasing the wearer’s [[DrunkOnTheDarkside aggression]]. Interestingly Fury Mode gets retired the episode after it’s introduced, something of a rarity for this show. The reason for why is partly this trope and partly because the Fury Cells don’t last very long and are in short supply.
338** ''Series/PowerRangersDinoFury'' gives us the Dino Master Saber which grants the user a new Dino Master Mode and features an ultimate attack to one-shot any monster. The drawback is that the ultimate attack sacrifices the Zords and the wielder of the saber. When the Rangers learn about that drawback, they agree not to use it, [[spoiler:at least until Zayto decided to use it against the Nemesis Beast as nothing else they tried worked to bring it down.]]
339* Several times in the ''Franchise/StarTrek'' franchise, people bring up the dangers of jumping to warp inside a solar system -- and somebody does so anyway, usually as a sign that they've reached the GodzillaThreshold. This gets undermined, however, by all the times a starship does just that -- sometimes while still inside a planet's gravity well -- and nobody makes a big deal of it.
340** Subverted in the ''Series/StarTrekTheOriginalSeries'' episode "The Enterprise Incident", where Spock appears to kill Kirk using a powerful Vulcan technique called the "Vulcan Death Grip". In reality, this was part of a plan devised by Kirk, Spock, and Bones to infiltrate the Romulan ship, which involved Spock becoming a FakeDefector; Spock actually only used a more intense version of the more familiar Vulcan Nerve Pinch to render Kirk unconscious and make his vital signs undetectable, claiming he had killed him to win the Commander's respect. There was actually no such thing as a "Vulcan Death Grip". (They were counting on the Commander to not know that, as Kirk later told Nurse Chapel.)
341** The ''Series/StarTrekTheNextGeneration'' episode "The First Duty" involves a "space aerobatics" maneuver called the Kolvoord Starburst, which involves five ships flying at each other, then opening their plasma vents and evading at the last moment. Done correctly, their engines ignite the plasma and the resulting trail forms a star with a burst from the center. Done incorrectly, you get one or more exploded ships. The last time it was attempted in a public display a century before the episode, all five cadets were killed, and Starfleet Academy responded by banning the stunt entirely due to the unacceptable risk. [[spoiler:Turns out it was attempted again, and once again it ended in a crash; four of the cadets managed to get out this time, but there was still one fatality.]]
342** There's also warp speed saucer separation. This is because the moment the saucer leaves the stardrive it immediately starts losing speed. If they don't pull the stardrive away in time, they would crash.
343* Parodied in ''Series/TheSuiteLifeOfZackAndCody''. A secret technique in Croquet that allows one to go through every single loop, but carries a substantial chance of shattering ones' bones. No such technique does or could exist since it would require the ball to do multiple 180 degrees turns.
344* In ''Series/{{Supernatural}}'', Sam's [[PsychoSerum demon blood]]-drinking to power psychic abilities takes a toll on his sanity and turns him into an out-of-control addict. [[spoiler:It gets worse when it's revealed [[IDidWhatIHadToDo all he did]] was just so he'd be [[UnwittingPawn tricked]] into releasing Lucifer.]] Since then, he went cold turkey (...with some exceptions...). In order to finish the SelfSacrificeScheme to [[spoiler:let Lucifer possess him so he can [[HeroicSacrifice jump]] into Lucifer's [[SealedEvilInACan prison]] and prevent the world from being razed, Castiel says this requires for him to drink A LOT of blood.]] Castiel also hints that [[spoiler:Lucifer's]] current Meat Suit has to drink gallons of demon blood just to keep him in.
345* Even Franchise/SuperSentai is not immune to this trope, as these three examples show.
346** ''Series/MahouSentaiMagiranger'' also has one. Anyone who uses Chronogel's forbidden time spell will die via getting sucked into a wormhole that appears on their chest while it sucks other things like matter and time into it. This curse was deliberately placed on it -- apparently, the use of time magic is so dangerous that ''making sure the universe is screwed if you use it'' is the best way to protect it. Yeeeah.
347** ''Series/JukenSentaiGekiranger'' features the Ju-Ju-Zenshin-Hen, which allows the user to take on a super-powerful beast-like form. The bad news: transformation is permanent. The worse news: if your technique isn't perfect, your life's gonna ''suuuuuuck.'' A Wolf Fist user winds up transforming into an out-of-control werewolf periodically, but at least he gets restored into his human form. The Fly Fist user (no, really) isn't so lucky, winding up an anthropomorphic fly who is about the size of a mouse. He ends up getting swallowed by an evil Chameleon Fist user and is resurrected along with her after she dies...
348** [[BewareMyStingerTail Stinger]] of ''Series/UchuSentaiKyuranger'' uses one that involves poisoning himself before he fights his brother in Space 20. [[spoiler:It heightens his fighting abilities, but also endangers him. Worse, his brother turns him against other Kyurangers.]]
349* ''Franchise/UltraSeries'': Many extremely powerfu; techniques and transformations are shown to be AwesomeButImpractical and even outright dangerous to their users.
350** ''Franchise/UltramanZero'''s most powerful form, Shining Zero, is extremely powerful as it can warp reality, reverse and control time and space, vaporize spirits and non-corporeal beings, and even undo black holes, but it also puts a lot of strain on Zero, burning through his stamina in seconds and forces him to rest after a single use.
351** ''Series/UltramanZ'': The D4 Ray is a powerful beam capable of vaporizing entire hordes of Kaiju and leveling city blocks, but it endangers its users and can leave dangerous dimensional cracks that if unchecked will eventually destroy the planet itself.
352** ''Series/UltraGalaxyFightTheAbsoluteConspiracy'': [[spoiler:Ultimate Shining Zero]] in addition to being AwesomeButImpractical has all the drawbacks of Shining Zero. [[spoiler:As such when Zero tries to fight Tartarus with it, he ends up defeated quickly as his energy runs out after a single BeamOWar with Tartarus.]]
353[[/folder]]
354
355[[folder:Manhua]]
356* The "Demon Ball" technique in ''Manhua/BowlingKing''. Its creator injured himself badly attempting to perfect it and was forced to retire from professional bowling.
357[[/folder]]
358
359[[folder:Pro Wrestling]]
360* A fair few wrestling moves involve both the opponent and/or the wrestler themselves landing on the ground, with the victim of a given move sometimes landing on their ''head''; Suffice it to say that even accounting for {{Kayfabe}}, wrestling is ''extremely'' dangerous.
361** Many regular folks (mostly kids) who haven't received proper training have tried out wrestling moves on each other and either seriously injured or killed the unlucky recipient, and as a result [[DontTryThisAtHome the bigger companies have actively shunned "backyard wrestling" in all its forms.]]
362* Some moves can cause lasting damage to the performer's body. The two most glaring examples are the moonsault and the tombstone piledriver, both of which involve landing full force on the knees. The repeated stress of the latter move is why Wrestling/{{Kane}} switched finishers to the chokeslam and why Wrestling/TheUndertaker developed the Last Ride.
363** The piledriver has been this since Wild Bill Longson invented it and used it to defeat and injury returning veteran Strangler Lewis. The Missouri athletic commission immediately banned the hold but Longson continued to use it with the justification of it being [[EasilyDistractedReferee behind the backs of the referees.]] He also campaigned to have it unbanned when he challenged Wrestling/LouThesz for the World Heavyweight Championship.
364** Speaking of the piledriver, an actual piledriver (not the tombstone version that the Brothers of Destruction use - that variant is ironically a lot safer to perform and receive) is something that WWE superstars haven't been allowed to use for over a decade due to Wrestling/OwenHart using the move on Wrestling/StoneColdSteveAustin, giving him the neck injury that would eventually end his career (no offense to Owen). Come 2013, the fact that Wrestling/CMPunk used it at all, let alone on Wrestling/JohnCena (who's had a history of neck problems), upped the JustForFun/HolyShitQuotient of the match they were in. Said match is now considered one of the best TV matches in RAW history. That being said, that's the only time the move has been used in WWE since the original ban — Punk and Cena were only able to get away with using it because they were the two top draws of the company at the time.
365*** Speaking of the piledriver some more, there's an even more devastating variation of it known as Kudo Driver, the Vertebreaker to you WWE fans, considered one of the most dangerous moves in all of wrestling. It's like a piledriver except, instead of holding your opponent upside-down in front of you by their torso, you hold them upside-down ''behind'' you by their ''arms,'' with the two of you back-to-back. This means their arms are restrained and there's no way to use your legs to cushion the impact. GarbageWrestler promotion Wrestling/{{FMW}}'s second-biggest star Megumi Kudo invented it, where it was ''[[BloodSport still]]'' one of the tamer ways to end a match there. Unsurprisingly, WWE banned it in 2003, but it's still used by wrestlers in other, more reckless promotions, such as by [[Wrestling/CheerleaderMelissa Mariposa]] on Wrestling/LuchaUnderground.
366** Wrestling/HulkHogan with the Legdrop and Wrestling/StoneColdSteveAustin with the Stone Cold Stunner. Landing directly on your ass hundreds of times a year must be great for the spine and neck (yup, they're connected).
367* Most aerial techniques, but the 450 Splash and the Shooting Star Press are really bad; not only do they wear your body down over time, but messing up could seriously hurt you on the spot. Just ask Wrestling/BrockLesnar.
368** Wrestling/BookerT's Harlem Hangover (a top-rope flipping Guillotine Legdrop) combined the wear and tear of aerial moves and legdrops. Back problems caused him to abandon the move after only a few years of use.
369* The diving headbutt, and German Suplex (which puts a lot of pressure on the spine), especially nasty since they were both signature moves of Wrestling/ChrisBenoit and may have caused the brain damage that resulted in [[PaterFamilicide the deaths of himself and his family]].
370* Technical wrestlers generally avoid this as most submissions don't actually put that much pressure on the body. That said, WWE has discouraged many holds which involve the user bridging on their neck, most infamously Wrestling/BryanDanielson's cattle mutilation, often making mat segments less impressive than those of the other majors.
371* Certain moves can get banned as part of a wrestling angle, usually by a heel authority figure.
372** Banning the piledriver and its many derivatives is a [[SevenYearRule stock plot]] in professional wrestling, especially in Memphis during the territorial era and Mexico City even after the territories fell. In fact, the banning of the move is ''why'' there are so many [[LoopHoleAbuse derivatives of it]], though just as common is the heel simply sneaking the move behind the referee's back (Wrestling/PaulOrndorff was especially notorious for doing it, RickyMorton the most famous victim).
373** At the 2007 Survivor Series, Wrestling/ShawnMichaels and Wrestling/RandyOrton faced each other in a title match where Michaels would get disqualified if he used his finisher, the Sweet Chin Music. To even up the odds, however, Orton's championship would go to Michaels if he got himself intentionally disqualified or counted out. [[spoiler:Orton won the match due to Michaels getting distracted trying to use the move but stopping himself, but then used it on him after the match was over.]]
374** In 2008, Wrestling/VickieGuerrero banned The Undertaker's then-recently-added submission move Hell's Gate. Her reasoning was due to it causing superstars to get injured and cough up blood. She would strip Undertaker of his World Heavyweight Championship for creating it in the first place, and the ban wouldn't get lifted until over a year later by Wrestling/TeddyLong.
375** In 2011, Vickie would strike once again, this time banning Wrestling/{{Edge|Wrestler}}'s spear briefly, and firing him for using it. One week later, Teddy Long once again lifted the ban and reinstated Edge.
376** In 2012, after Wrestling/{{Sheamus}} accidentally hit Ricardo Rodriguez with a brogue kick instead of intended target Wrestling/AlbertoDelRio, Del Rio and Wrestling/DavidOtunga tried to push general manager Booker T to ban the move. Booker briefly banned it while investigating whether or not to ban it permanently, but shortly after pointed out that they should understand the risks involved in pro wrestling, and lifted the ban on the move.
377* The Burning Hammer[[note]]Putting the opponent on your shoulders in an Argentine Backbreaker position and then ''dropping them straight on their head''[[/note]] is considered to be flat-out the most dangerous move in all of Professional Wrestling. An "inverted Death Valley bomb" was first used Kotetsu Yamamoto in the 1970s and then apparently not attempted again for another ''twenty years''. The innovator of the version made famous in Wrestling/AllJapanProWrestling, Wrestling/KentaKobashi, has only used it seven times in his entire career, and every single time [[GodzillaThreshold it has put away the opponent for good]]. This fact just added to the JustForFun/HolyShitQuotient during the Wrestling/WWECruiserweightClassic where [[spoiler:[[Wrestling/LondonAndKendrick Brian Kendrick]], a veteran who was doing anything he could to stay in the tournament, used the move against Wrestling/KotaIbushi in a last-ditch effort to beat him. And even then, it wasn't enough to put Ibushi away.]]
378* On that note, the Ganso Bomb, essentially a marriage between a powerbomb and a piledriver wherein the opponent is dropped right on their own neck. It's about as dangerous as the Burning Hammer, perhaps even more so. For decades Wrestling/MitsuharuMisawa and Wrestling/ToshiakiKawada were the only two wrestlers willing to do it and even then only did it once in an era where Wrestling/AllJapanProWrestling was otherwise all about SerialEscalation.
379** This is because the first Ganso Bomb was, in fact, an ''accident''. Around eight minutes into Misawa and Kawada's January 1999 title match, Kawada delivered a spinning backfist to the back of Misawa's head with such force that he broke his right forearm and wrist. While Kawada ''continued to wrestle for fifteen minutes'' (he was booked to win the match, but he vacated the title the next night due to the injury), he was unable to lift Misawa all the way for a powerbomb, and the ganso bomb was an improvised solution.
380* Right behind the Burning Hammer and Ganso Bomb, sittingly comfortably next to the Kudo Driver, is The Muscle Buster, a move that originated not in the ring but in the ''Manga/{{Kinnikuman}}'' manga comic after the mangka saw Mexican luchador Chamaco Valaguez's La Valagueza submission hold and thought Wouldn't that hurt more if he dropped to the mat and drove the other guy's neck into his shoulder?". Wrestling/AllJapanProWrestling heavyweight Kodo Fuyuki was the first man crazy enough to try it in the ring, but most wrestlers use Wrestling/SamoaJoe's safer variation where he always grabs the opponent from the top rope while standing on the mat, walks to the middle of the ring and falls backwards in a suplex motion that puts the recipient on his back. This more cautious method was used by Joe for over a decade with minimal incidents until it was called "reckless" by Wrestling/BretHart after it damaged Tyson Kidd's neck and sent a shock down his spinal chord, making Tyson fear he was paralyzed. Tyson wasn't but still ended up hanging up taking WWE's offer to become an agent and hanging up the boots. Still, Wrestling/{{Ryback}} used a single leg variation of Joe's variation on WWE television, lifting the recipient straight from a standing position in a fisherman's suplex manner, dubbing it "shell shocked".
381* The Styles Clash, a variation of Colonel [=DeBeers=]'s own double underhook facebuster variation that instead lands the opponent on his chest, is fairly safe by pro wrestling standards. The "defender" has very little work to do and the "attacker" role is not very complex, which is amazing considering it originated not from an attempt to improve on [=DeBeers=]'s move but from a ''[[ThrowItIn botch]]'' of the much more dangerous powerbomb, which in almost every other situation require a lot of work on both sides to be safe. Ironically, The Styles Clash ''is'' a really dangerous move if taken improperly. Wrestling/YoshiTatsu botched receiving it and ended up with a broken neck, but Wrestling/AJStyles has grown attentive and actually saved James Ellsworth from injury by noticing he tucked his chin[[note]]tucking your chin forward is the normal way to protect yourself when receiving most moves, but as the Styles Clash is an ''inverted'' mat slam this is the ''opposite'' of what you're meant to do to protect your neck in this case[[/note]] and landing on his hands.
382[[/folder]]
383
384[[folder:Puppet Shows]]
385* ''Series/PiliFantasyWarOfDragons'': Learning the Tenth Bodhisattva Seal causes the practitioner to die seven days later as their internal organs are crushed within. This is incredibly inconvenient (aside from the obvious reasons) because it is the only way to save someone from the delayed death effects of the Illusory Fist attack. And a meat shield who will die is needed in front of the person they intend to save, at that.
386[[/folder]]
387
388[[folder:Roleplay]]
389* In ''Roleplay/DawnOfANewAgeOldportBlues'', Josephine has a special technique that [[ElementalShapeshifter transforms her into ice]], constantly generates [[ShockAndAwe electricity]], and boosts her other abilities by a significant degree. It's so powerful that, were she to use it, she'd likely die from the strain.
390* ''Roleplay/NothingIsSacred'': Going to a card shop. [[MyGodYouAreSerious Yes, really]]. Stella has [[BornUnlucky terrible luck]] with almost anything chance related, which means that she never draws good cards from card packs. This forces her to instead get her cards by trading her magical energy for them from the denizens of the SpiritWorld, but she eventually finds another method. After a few lessons in magic, Stella learns a technique that allows her to draw any card she desires from a pack by expending a bit of spiritual energy. This gives her the ability to acquire some amazing cards such as Monster Reborn, Heavy Storm, and Raigeki, but it also acts as a magical beacon to any spirit that can sense it, which means Stella has to strictly limit the use of her new ability lest she attract the attention of some very unsavory spirits.
391[[/folder]]
392
393[[folder:Sports]]
394* The ''barra vasca'' style of javelin throwing. Originally stemming from a Basque martial art, it is basically throwing the javelin as if it was a discus. The ''barra vasca'' is an immensely effective style, and a new world record was immediately made. The Finnish javelineers got enthused about this style and soaked their throwing hands in soapy water, inventing the "soap style" with which the javelin flew well over 95 m. Needless to say, the accuracy of ''barra vasca'' style is appalling, and only some 10% of the throws ever got in the sector -- some throws even landing in the grandstand, endangering the spectators. The style was explicitly prohibited beginning with the Melbourne Olympics in 1956.
395* Amusingly, many then-standard pro wrestling moves, such as any and all elbow strikes, headbutts, and [[KickThemWhileTheyAreDown kneeing the heads of downed opponents]] were quickly outlawed in Shooto's formative years. There was an ongoing debate regarding punching the back of the head for fourteen years before it was officially banned too. In the wider Usefulnotes/{{mixed martial arts}} community branching out from Shooto, the debate is over whether to ban ankle locks or not. The fact that applying an ankle lock is a good way to be put in one is the only reason why debates exist.
396* Fans of Japanese MMA are often surprised to learn [[KickThemWhileTheyAreDown soccer kicks]], among the most effective and reliable fight-ending tactics, are banned almost everywhere outside of Japan.
397* Within elite gymnastics, there are a number of moves that are banned.
398** On floor exercise, all roll-out somersaults[[note]]save for the simple dive roll, which is so easy it only ever appears in elite floor routines as choreography anyway[[/note]] are banned. These skills were banned for women in 1993, which is credited to the paralysis of Russian star gymnast Elena Mukhina while attempting one such skill in 1980; the 2017 code of points also banned these skills for men.
399** On women's uneven bars, all skills that involve standing on the bars, which were at one time relatively common, are now banned. Notable skills in this category include the Korbut Flip[[note]]a backflip from standing on the high bar[[/note]], the Layout Backwards dismount[[note]]a backflip over the low bar from standing on the high bar[[/note]], and the Mukhina Salto[[note]]a Korbut Flip with a full twist[[/note]]. The reason for banning these skills appears to be partly for aesthetic reasons [[note]]stepping up onto the bar often breaks the flow and rhythm of a bar routine, which is why other, much less risky skills in the same vein, like the low-to-high jump, are also part of the ban[[/note]] and partly because of safety concerns.
400** In 1988, Julissa Gomez was performing a Yurchenko vault (a vault with a round-off entry) when her foot missed the springboard, which pulled her body downwards so that instead of going over the vaulting horse, she crashed headfirst into it, breaking her neck and leaving her paralyzed (she would die a few years later of complications from the injury). Following her accident, the international gymnastics board ruled that a "safety collar" mat must be placed around the springboard for any vault with a roundoff entry to prevent exactly this potential mishap[[note]]the safety collar doesn't give as good a rebound as the springboard, but it keeps the missed foot level with the springboard instead of creating the downward pull; the subsequent vault would probably be very low in flight, but it would get the gymnast over the table[[/note]]. If a roundoff entry vault is performed without the safety collar, it's an automatic zero. An unusual example in that they didn't fully ban the skill but rather banned doing it without the proper safety equipment in place. (Other changes to the equipment were also introduced.)
401** Also in women's gymnastics, the [[https://en.wikipedia.org/wiki/Produnova Produnova]], known as the vault of death, has a reputation for its high risk of injury. Unfortunately, because of its high value, some gymnasts would attempt it even if they knew they couldn't get it around, knowing they'd still get a reasonably good score even with a fall, which means they have a much smaller margin of error to avoid a catastrophic landing should something go wrong. Ahead of the 2017 quad, the FIG finally took action to stop this happening, and very cleverly managed to do so without banning the vault entirely -- rather, they introduced a rule that automatically devalues the vault if the gymnast "lands on the feet and any other body part simultaneously". This way, a gymnast who can actually land the skill consistently (like the eponymous Produnova could) can still do it and get credit, but a gymnast who can't won't have an incentive to put themselves in danger trying to do it anyway. This is another case where safety is likely only part of the reason, as there were also concerns about gymnasts [[LoopholeAbuse exploiting the value of the vault]] to get into finals, even with a fall, over gymnasts doing better but simpler vaults.
402*** Averted with its Yurchenko equivalent, the Yurchenko double back (a roundoff entry onto the springboard, followed by two flips in the air before landing). Despite the fact that this vault is considered even ''more'' dangerous (while the "Prod" could very conceivably result in spinal injuries if missing enough rotation, the chance is lower than in the double back, as due to the mechanics of forward vs. backward rotation, an under-rotated front flip is more likely to end up with a gymnast landing flat on her back, which isn't especially likely to cause major injury, but an under-rotated backflip has a good chance of landing on the ''head''), there are no special rules pertaining to it, only the aforementioned safety collar rule that applies to all backward vaults. In fact, when Simone Biles became the first woman to perform the skill in international competition, she ended up being assessed a 0.5 point deduction for the presence of a spotter, despite said spotter being obviously there to provide an extra guard against serious injury with such a risky skill.[[note]]Biles had been warned in advance that she would be deducted for having a spotter, but decided to do it anyway because she felt the risk of injury outweighed the loss of points.[[/note]] However, while it's never been banned internationally, Marta Karolyi did effectively ban the skill for USA gymnasts during her tenure as National Team coordinator: the first time she saw [=McKayla=] Maroney (widely considered the greatest vaulter in the history of the sport) attempt the skill at a national team training camp[[note]]almost certainly onto something much more forgiving than a regulation landing mat[[/note]], Karolyi very firmly told her to "Never do that again!!" and then chided Maroney's coach for allowing it because she was so afraid that Maroney could be catastrophically injured. While she might not have outright made this a written rule, this reaction sent a clear message that even training this vault wouldn't be allowed as long as she was in charge of the program (much to Maroney's disappointment, since she wanted to be the first to compete it internationally on the women's side). The moratorium clearly ended with Karolyi's retirement, though, since Biles was allowed to train and perform the skill in the subsequent quad.
403* Figure Skating:
404** The Backflip is a well-known example of a banned element within the sport, being outlawed in 1976 shortly after Terry Kubicka became the first and only skater to legally land the trick in competition. The trick's notoriety is largely thanks to Surya Bonaly, who after dropping out of medal contention at the 1998 Olympics, performed a backflip and landed on one foot as a crowd-pleaser, penalty be damned. The Backflip overall is a bit of an unusual example of this trope, as it isn't especially dangerous and it remains a staple of exhibition shows to this day; most likely it was banned for being a highly atypical type of jump that also isn't exactly elegant to pull off in the middle of a routine.
405** In Pair Skating, all lifts must be hand-to-hand, arm, body, or upper leg. This subsequently outlaws a range of dangerous lifts, such as those that involve the Lady balancing precariously on the Man's head, shoulders, or back, as well as 'Headbangers' that involve swinging the Lady so that her head passes uncomfortably close to the ice. Like Backflips, these elements remain common sights at exhibition shows, but their risks keep them out of competitions.
406* Judo has four forbidden techniques that are banned from official competitions because of the risk of severely injuring the opponent. Aside from the ''Kani-Basami'', an [[https://youtu.be/h1KPk5-ab2w extreme footsweep that requires a certain athleticism to be executed]], they are not that hard to pull off.
407* In Gridiron Football and Rugby both, the Flying Wedge is a dead simple and extremely effective formation, but is so dangerous (the formation has resulted in ''deaths'' in the past) that it and other related formations were banned within two years and have been eradicated completely from both sports.
408[[/folder]]
409
410[[folder:Tabletop Games]]
411* ''TabletopGame/BlueRose'' has Sorcery, generally banned in most kingdoms, to the point that legalizing the ''study'' of sorcery in Aldis has been greatly controversial. While arcana are generally legal in Aldis, sorcery allows an adept to directly harm, control, or invade other individuals, mentally or physically, as well as create undead or summon [[OurDemonsAreDifferent darkfiends]], and are considered crimes against all sentient beings. Trying to classify sorcery is tricky, as few arcana are clearly sorcery, and even those that are can be wielded for a period of time without any real damage to the adept if he is sufficiently resilient. Unfortunately, sooner or later, TheCorruption takes hold, and the adept will either fall into the arms of [[DarkIsEvil Shadow]], die a painful death, and become transformed into a walking corpse, or try to cleanse himself even as corruption makes it harder. Many people who use sorcery are scrupulous enough to embrace the corruption that comes with it, but the temptation is always there for any arcanist, even those with the best intentions.
412* ''TabletopGame/ChangelingTheLost'' features Goblin Contracts, magical powers that are cheaper to buy than standard Contracts and have nice effects (open all the locks on a building, see the future, drain an enemy of all their [[{{Mana}} Glamour]]). The catch? Well, they also have side effects that will likely screw you over (respectively, your locks fail the first time someone tries to break in, [[MadOracle you go mad]], you lose all ''your'' Glamour).
413** One particular Goblin Contract is "[[TheWildHunt Call the Hunt]]" which has no real catch because it is its own catch; it calls forth a hunting party of [[TheFairFolk True Fae]]. If the changeling who uses it doesn't run away fast enough, he or she will likely be killed or, even worse, dragged back to Arcadia to be tortured once again.
414* Overuse of what ''should'' have been a Dangerous Forbidden Technique -- defiler magic, powered by the life force of creatures and the natural world -- is what made Athas, the planet where ''TabletopGame/DarkSun'' is set, into a desolate wasteland.
415* ''TabletopGame/DemonTheDescent'' features a technique called "Going Loud". In simple terms this transforms your character into their demonic form, sets your magic [[PowerLevel Power Level]] (called Primum) to 10 (out of a maximum of 10) completely refills your Mana (And having maxed Primum means you are able to hold LOTS of Mana) and allows you access to basically ALL of the magic spells in the game. The catch? Well, the whole point of this game is that Demons need to impersonate a human in order to avoid the attention of the game's BigBad. The human identity they adopt is called their "cover" (in the espionage sense of it being a cover identity). Going Loud irrecoverably destroys that cover, effectively erasing every detail of it from existence, which means that the Big Bad knows ''exactly'' where you are...
416** There are also Exploits, incredibly unsubtle delays of power that can do anything from resurrecting the dead to causing rains of fire to kill somebody so hard, it erases their last action from existence. Every one of them requires a Compromise roll, which may not ''destroy'' the Cover, but can certainly damage it.
417* In the ''Literature/{{Dragonlance}}'' setting, Wizards of High Sorcery view Primal/Wild Sorcery this way. It was three Sorcerers who, fighting an army of Dragons at the end of the Second Dragon War, caused magical storms that wracked Ansalon. These three Sorcerers ended up becoming the first Wizards after being taught High Sorcery by the gods of magic.
418* ''TabletopGame/DungeonsAndDragons'':
419** There exist two magic staffs in the game, the ''staff of power'' and the artifact ''staff of the magi'' which, while very powerful items in themselves, can be broken for a "retributive strike" which releases every spell inside the staff at once, centered on the caster. Given that the SquishyWizard is the norm, anyone attempting this strategy had better hope that the 50% chance of getting sent to another dimension comes up.
420** There also exists an incredibly powerful dispel spell called ''Mordenkainen's Disjunction'', which can destroy just about any magic effect, even those created by gods. If it is used for this purpose, however, the caster may permanently lose all his magic abilities and/or anger the effect's creator. And he is no slouch, believe us.
421** ''Complete Arcane'' has a 9th-level wu jen spell called ''Transcend Mortality'', which you're not supposed to use except in desperation. It basically makes the caster NighInvulnerable (and its casting is an immediate action, meaning it can be invoked right before an attack hits) and last for about one combat. However, once it expires, the caster instantly dies and is disintegrated.
422** This is the point of the corrupt spells in the ''Book of Vile Darkness'' (and their ''Exalted Deeds'' counterparts, sanctified spells). They are notably more powerful than other spells of their level -- for instance, run-of-the-mill ''Blindness'' is a second-level spell, while ''Seething Eyebane'', a corrupt first-level spell, causes the target's eyes to spew acid and explode -- but there is always a tax, sometimes permanent, on one or more ability scores. The most powerful of these spells is harmful even to prepare and has a very good chance of rendering the caster dead and/or permanently insane [[OmnicidalManiac (if he wasn't already)]].
423** Something else mentioned in the ''Book of Vile Darkness'' is the ArtifactOfDoom called the [[NamesToRunAwayFromReallyFast Death Rock]]. Artifacts are always dangerous, but this one is worse than most; its history does say that its owners tend to obtain great power and are able to conquer empires, but tend to lose the power at the worst possible time, and are usually overthrown in violent insurrections by their enemies. Here's how the Rock works: It gives the user incredible dark powers of [[{{Necromancer}} necromancy]], giving him the potential to raise vast undead armies. But it has a terrible cost; once a week, it demands the user slay his closest friend or loved one, and claim him or her as a zombie slave. If he is unwilling or unable to do so, the Rock and all powers associated with it vanish. Clearly, all former users never realize that if you are willing to do this, you're going to run out of friends and loved ones ''very'' quickly (a lot of them will likely stop being your friends before you can use them as the required sacrifices) and be unable to make any new ones; on the other hand, you'll probably make hated enemies ''very'' fast...
424** Prior to the 2nd Edition, Orcus was murdered by Kiaransalee, the drow goddess of undeath, who usurped his realm in the Abyss. However, in the ''Dead Gods'' module, he CameBackWrong, becoming an undead demon named Tenebrous, possessing a spell called the Last Word that was so lethal, even gods were afraid to use it. This didn't stop Orcus, however. Despite the fact that it was literally consuming him from within, he used it in his campaign to restore himself to life killing several gods using it in order to reclaim [[ArtifactOfDoom his Wand]], and regain his domain in the Abyss. (He succeeds in doing all that, but fortunately, failed in his ultimate goal: becoming a true god.) After gaining back his true form and position, he lost the ability to use it. (The gods have since taken steps to prevent anyone from using it again.)
425** From 3.5 edition's ''Tome of Battle: Book of Nine Swords'', the Shadow Sun Ninja PrestigeClass is a class of good-aligned warriors that accept the dark aspect within themselves and not reject it, allowing them to use the power of both sides. The final ability they learn, Balance of Light and Dark, lets their inner darkness run rampant, transforming themselves into a shadow form with a number of special immunities, causes negative energy spells used on them to heal instead of harm them, a bonus to Hide skill checks, and attacks made when in areas of darkness or shadowy illumination. It also grants the Shadow Sun Ninja the option to inflict ''negative levels with no saves allowed'' and heal a small amount of damage with every successful unarmed attack they make.[[note]]Improved Unarmed Strike is a prerequisite feat for the Prestige Class[[/note]] However, for every negative level the Shadow Sun Ninja inflicts this way, they also take a point of Constitution damage once their transformation ends. Low on HitPoints at the end of the shadow form? A character can drop dead from the sudden HP reduction due to CON lost. But wait, it gets worse. Hit 0 CON? The character doesn't even return back to normal, instead dissipating into an inky dark cloud. That starts a 1 to 4-day random time limit to bring the Shadow Sun Ninja back to life, and only the spell ''True Resurrection'' will work. Run out of time [[spoiler:and then the Shadow Sun Ninja's body reforms as an NPC vampire, shifts immediately from whatever good alignment they were straight down to a champion of evil, has all of the Prestige Classes abilities, oh and they don't have the normal vampire's vulnerability to sunlight. Once this occurs, slaying the vampire still won't let the Shadow Sun Ninja be returned to life with any spell. The only way to save them at that point, is for their allies to travel to the Iron City of Dis located in Hell and free their trapped soul being imprisoned there, which will instantly slay their vampire self if it still exists and restore them to life.]]
426** The Wish spell in 5e works like one of these; use it to cast any spell of 8th level or lower? No problem. Use it to cast a 9th level spell or to cause ''any'' intended effect that the user wishes (and the DM deems appropriate)? This is the tricky bit. After using Wish in the latter way, any spell you cast until a long rest will do an unavoidable d10 of necrotic damage, as well as reducing your Strength stat to 3 for 2d4 days. The real kicker comes with the 33% chance that the player who cast Wish will ''never'' be able to cast it ever again, throughout the fullness of that character's existence.
427** Another 5e example: Evocation Wizards can "overcharge" their spells to maximize their effectiveness. Doing so once is harmless. Doing it again does a fair bit of damage, which increases drastically from that point on.
428* Plenty of Charms in ''TabletopGame/{{Exalted}}'' come with heavy tolls. The more common include pushing up your Limit track, and Abyssals have some that increase resonance or mean that they'll experience CessationOfExistence upon death.
429** The Infernal Exalted get a good number of these, mainly because they're learning Charms that make them more like their [[EldritchAbomination Yozi]] patrons. Learn a Charm that gives you increased authority over lesser demons? That means greater demons are allowed to walk all over you. Learn a Charm that perfectly blocks Social attacks? That's because it turns all noise into wretched discord that makes you want to kill. Learn a Charm that allows you to communicate telepathically? Shame you can now only vocalize laughter for the rest of your days.
430* ''TabletopGame/GeniusTheTransgression'' has Deep Inspiration, which lets you draw out Mania directly from the Genius's mind, even if the Genius is "empty". Unfortunately, doing so too often or with too much power runs a very real risk of turning you into an [[InsufferableGenius Unmada,]] and if you keep pushing it even after becoming Unmada...[[TheUnfettered It's a bad idea]].
431* The [[WordsCanBreakMyBones Words of Power]] from ''[[TabletopGame/{{GURPS}} GURPS: Thaumatology]]''. Saying one will knock most characters unconscious and the most control you can ever have over a Word is none at all, trying to control it only makes things worse.
432* ''TabletopGame/HcSvntDracones'': Transcendent implants at Cuil 3 or higher generally have a significant chance of causing messy, painful death for their owners, it's guaranteed if someone at Cuil 5 tries to use their implant. Oh, and the Cuil level of an implant temporarily increases each time it's activated in combat.
433* In ''TabletopGame/{{Ironclaw}}'' [[BlackMagic Unholy magic]] (such as Necromancy, offensive Lutarist spells, and a few Druid curses) summons vengeful spirits to do magic for you, there is a chance that these spirits will do other things like animate random corpses, possess people (including the caster), or make scary sounds that freak people out (sometimes to death).
434* In the Sorcerer game from the ''TabletopGame/MageTheAscension'' line, there is one Path that can have this effect: Cursing, which is ExactlyWhatItSaysOnTheTin. Specifically, you can create an absolutely ''vicious'' curse rather than the normal version. The problem is, though, that it renders the caster a vegetable.
435* ''TabletopGame/MagicTheGathering'':
436** The game has a bunch of cards that are effectively this. You can't miss them, because they all inform you that ''you lose the game'' after a certain amount of time or if a certain condition is met. For example, [[HourOfPower Final Fortune]] allows the user a free turn at a cost and color that doesn't normally get it, but the user loses the game at the end of that turn if they haven't won yet. [[{{Immortality}} Lich and its variants]] protect you from dying through life loss, but kill you under other circumstances, such as an empty graveyard.
437** For Black, there is no technique dangerous or forbidden enough ''not'' to use. In story terms, it is the color that regularly makes use of [[{{Necromancy}} death magic]], [[DealWithTheDevil bargains with demonic beings for power]] and [[PowerAtAPrice paying the price for that power without a second thought]]; Mechanically, many cards require either a payment of life points or the sacrifice of a creature upfront as payment or repeated payments over time for upkeep. The logical extreme of this mentality is the "Suicide Black" deck, an aggressive deck that uses cards like [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=397570 Carnophage]] which are powerful for their mana cost but possess drawbacks that ''will'' kill you if you don't win quickly. It's referred to as "tearing your arm off and beating your opponents to death with it before you bleed out".
438** The best definition of this trope is the card Demonic Pact. Each turn, you ''must'' apply one of its effects, but you can't use the same one twice. These effects are draining a sizable chunk of someone's life, making an opponent discard 2 cards, draw 2 cards yourself, and ''losing the game''.
439* In the ''TabletopGame/{{Mystara}}'' setting, Glantrians' use of the Radiance is considered this trope even by the Alphatians, who normally consider even the darkest sorts of magic to be permissible. This isn't because it's dangerous to the wielder (which it is), but because [[spoiler:using the power of the Nucleus of the Spheres threatens to drain all magic from the world, bit by bit]].
440* ''TabletopGame/PrincessTheHopeful'' has the Royal Favours power of the Court of Storms. Once per session, the player may declare that the Queen of Storms is manifesting power through their character. This lets her use any Tempesta or unaligned Charm with a rating of half the character's Tempesta or less, with as many successes as the player wants and none of the normal costs. The catch? The character also [[CastFromHitPoints takes Resistant Lethal damage equal to the number of successes chosen]], and the book specifically states that the Queen of Storms has killed her own soldiers in this way.
441* ''TabletopGame/PrometheanTheCreated'': A Promethean who immobilizes another Promethean can perform something called the ''lacuna''. The exact mechanics of this are uncertain, but it allows the performing Promethean to rob [[ExperiencePoints vitriol]] from their victim. While this can be a hell of a windfall, it is also considered one of the worst possible things one Promethean can do to another - it amounts to ripping away the victim's progress in their [[BecomeARealBoy Pilgrimage to becoming human]] in the name of petty, short-term gain. It [[VideoGameCrueltyPunishment automatically costs the performer a point of]] [[KarmaMeter Humanity/Pilgrimage]], and any Promethean who performs it more than once is likely too selfish to ''ever'' finish their Pilgrimage. But sometimes, if you're absolutely ''desperate'' for power...
442* Several of the noble families from the ''TabletopGame/{{Ravenloft}}'' supplement ''Legacy of the Blood'' possess the knowledge of a Dangerous Forbidden Technique or two, usually in the form of feats that only family members or their elite henchmen can select.
443* ''TabletopGame/{{Scion}}'' has the Avatars, which allows Gods to channel the power of a Purview at the apex of cosmic power, so much that anyone who fights them has to become one in order to match. However, while the cost to activate it is rather modest game-wise, there are some major prices to be paid: first, you suffer the strongest Fatebinding upon activation, second, if you die, all the Avatars you learned to channel get loose all at once, and third, you activate it in the domain of a Titan, you'll attract every Titan Avatar in it, and chances are, they'll already have their own powers ready as well. Congrats, you now get to fight five or six beings with the same power as you.
444* In ''TabletopGame/Warhammer40000'', any Psychic Power that requires 3 Warp Charges is this. You only harness a Warp Charge on a roll of a 4+, which means that, on average, you'll need to roll two dice for every 1 Warp Charge requirement, and probably significantly more if you MUST have it go off. This means that you will need about 6-9 dice to reliably use a 3 Warp Charge Power. Given that the average army's psykers can maybe get 10 dice to use in total (and that's if you're lucky) this is a significant investment of resources. You also have to declare all the dice you want to use for the attempt before rolling them; if you choose 7 but five came up a dud, the remaining two are wasted. On top of that, if any harnessing attempts result in 2 or more 6's, the Psyker perils and has a chance to be devoured by Daemons (which can result from such pleasantries as being flat out removed as casualty to simply forgetting the spell then taking a punch to the nuts). Worse if you decide for him to roll on one of the Daemonology Disciplines without being the proper faction (Grey Knights for Sanct, Daemons for Malefic); this table perils on any sets of doubles, not just two 6's.
445* In ''TabletopGame/{{Warhammer}}'', elves taught humans magic using a Dangerous Forbidden Technique that lets the student master one color of magic in a very short period of time (a decade or two), at the cost of it inevitably driving them insane... [[LoopholeAbuse in two or three hundred years]].
446* The ''TabletopGame/YuGiOh'' card game has a few perfectly legal cards that could be considered this. One is [[http://yugioh.wikia.com/wiki/Destructive_Draw Destructive Draw]]. It's a Continuous Trap that lets you draw twice during your Draw Phase if you have no cards in your hand when you start your turn. ''However'', you take 700 points of damage per turn, and unlike most cards like this, it's possible to lose the duel this way. Also, this card is hard to get rid of; doing so causes the player who uses it 3,000 points of damage.
447** At least there are ways to turn that one to your advantage, like Prime Material Dragon. And the even worse card is [[http://yugioh.wikia.com/wiki/Lucky_Punch Lucky Punch]]. This is also a Continuous Trap, and it lets you toss three coins once per turn when your opponent attacks. Get three heads, and you get to draw three times. (That's only a 12.5% chance, by the way.) Here's the catch: If you get three tails, the card is destroyed, and if it's destroyed in ANY way, you lose 6,000 Life Points. (Because it isn't considered damage or a Life Point payment, there's really no way to avoid it or convert it to Life Point gain.)
448[[/folder]]
449
450[[folder:Toys]]
451* Nova blasts from ''Toys/{{Bionicle}}'', during which the Toa unleash all of their ElementalPowers in a [[FantasticNuke massive explosion]]. Not only does it leave the Toa with no power left, depending on the type of element, it can also easily kill anyone in a close (or even not-so-close) vicinity. As the Toa adhere to a strict ThouShaltNotKill code, the idea of a nova blast is unthinkable, and thus it is the ultimate GodzillaThreshold for a Toa. Only two nova blasts were ever initiated throughout the story's length: the first [[spoiler:by Gali Nuva]] sank an entire island, and was only activated as a last resort to defeat a powerful Makuta after the island's evacuation, which the Makuta survived; while the second [[spoiler:by Jaller]] was being charged up as a desperate attempt to buy one of his teammates enough time to undo the Great Spirit's death and consequent collapse of the universe, even if he would incinerate the rest of his team in the process (fortunately, this situation resolved itself before he actually had to release the blast, and he just barely got it under control before releasing it and consequently [[spoiler:taking all of Metru Nui with him after his team was teleported there]]).
452* In the ''Toys/MonsterHigh'' franchise, Frankie weaponizing her body's electricity by swapping the bolts on her neck is shown to be this, as when she does it on her grandfather's rampaging robot she consequently suffers a HeroicRROD. She gets better through ThePowerOfLove.
453[[/folder]]
454
455[[folder:Video Games]]
456* ''VideoGame/AITheSomniumFiles'': A Psyncer can only safely stay in someone's Somnium for about six minutes; any longer carries the risk of mental damage from the subject's mind consuming the Psncer's mind. Date still chooses to go past the limit a few times while attempting to get crucial information, causing Boss to forcibly end the link. [[spoiler:In truth, the ''actual'' reason for the limit is to prevent a FreakyFridayFlip, which is irreversible]].
457* The Chaos Dunk from ''VideoGame/BarkleyShutUpAndJamGaiden'' is this for basketball, with the original one wiping out millions of people and getting B-Ball outlawed and [[spoiler:is implied to kill Barkley and Balthios when Barkley uses it to kill Shadow Barkley]].
458* ''VideoGame/BattleGaregga'' lets you "reprogram" autofire by manually tapping the fire button for two seconds to "record" a new autofire pattern, and you can raise the rate of autofire this way. However, raising the autofire rate will ''multiply'' the rate at which [[DynamicDifficulty rank]] increases over time, as explained [[http://shmups.system11.org/viewtopic.php?p=3508&sid=d8921368a406cd38032ffe98c9ff3d3a#p3508 here]], and the rank increase rate ''cannot'' be reduced once you raise it, meaning that attempting to give yourself faster autofire in the early game can spell disaster in the form of ridiculously aggressive enemies later on. It does have its applications, but those are left to advanced players who seriously know what they're doing.
459* ''VideoGame/TheBindingOfIsaac'' allows players to pick up many upgrades and abilities at random, some of which are very, very powerful. But there are many with heavy, even potentially crippling costs.
460** Ipecac changes one's tears into a strong explosive attack, at the cost of making them charge slowly and be able to hurt the player. In an added bit of irony, range-up effects or upgrades actually make Ipecac harder to use, as maxed range makes the projectile detonate far from the player. This means they'd need to hug the opposite wall just to have a hope of hitting a target in the middle of the room.
461** The Suicide Bomber vest (Named Kamikaze in ''Rebirth'') allows the player to use unlimited explosions, with the downside being they also take the damage. Because, you know, they are detonating bombs strapped to their chest.
462*** The major risks/downsides of Ipecac and Kamikaze can be negated if you get Pyromaniac though (Which causes explosions to heal the player). In the case of Kamikaze, this synergy essentially makes the player immortal with access to infinite, instant healing. This also works with Host Hat, which gives explosion immunity (Though you don't become immortal with Kamikaze if you use the Host Hat version, you can still spam it at no cost).
463** The Devil Rooms usually hold a number of power items, and while they vary from room to room they're relatively consistent. The problem comes from having to sacrifice heart containers to receive them. Not hearts, heart CONTAINERS. The player literally sacrifices their life for power. And that's not counting many of the items they get from the devil rooms have their own disadvantages.
464*** The Lost and his Tainted variant from ''Rebirth'' and ''Repentance'' respectively don't have to pay Heart Containers (because, y'know, [[OneHitPointWonder they don't have any]]), but they can only take 1 item per Devil Room.
465** ''Afterbirth+'' gave us Plan C, a consumable item that will kill '''ANYTHING''' in the game. Even bosses. ''Even the final bosses.'' The drawbacks? First, it only kills a single phase of a fight, so you can't use it to kill an entire fight with multiple phases. Secondly, ''it kills you 3 seconds later, bypassing all immunities/ invulnerabities''(though, extra lives can still proc if you have any), meaning that you basically have to end the run right there if you don't want to lose it. Doing this for unlocks also doesn't work on certain bosses, as their death animations last longer than 3 seconds.
466* ''VideoGame/BreathOfFireDragonQuarter'' had an extreme version of this. The main character, Ryu, can transform into a ridiculously powerful dragon form at any time which can even floor bosses in a few attacks. However, there's a % counter in the top-right corner of the screen that's slowly ticking towards 100% throughout the game, and using dragon powers make the counter increase much more quickly than it normally does - and if the counter gets to 100%, it's game over. Without dragon powers, the boss fights are quite hard (especially the later ones), so it's down to the player to manage how often they use the dragon powers.
467* ''Franchise/{{Castlevania}}'':
468** In ''VideoGame/CastlevaniaPortraitOfRuin'', it's stated that if anyone outside the Belmont clan uses the true power of the Vampire Killer, it will drain their life force and eventually kill them if they overuse it. When the whip's power is unlocked in-game, it can be used as much as you want with no negative consequences gameplay-wise, but it's likely that it would simply take longer than the few days the game seems to take place over for it to take a serious toll.
469** ''VideoGame/CastlevaniaOrderOfEcclesia'' has the Dominus glyphs; Dominus Anger and Dominus Hatred are direct attack glyphs that are incredibly powerful but [[CastFromHitPoints take off a solid chunk of your HP]], while Dominus Agony massively increases all your stats at the cost of constant damage over time. Unless you use a healing item at some point, prolonged uses of these glyphs by themselves will kill you. The Dominus glyph union outright kills everything in the area -- Shanoa included.[[spoiler:..unless you're using it at the end of the final battle, [[HeroicSacrifice when Albus lets his soul be the sacrifice instead]].]]
470* ''VideoGame/CopyKitty'': The {{Superboss}} of the game is a techno-magical abomination that wields the ultimate dark magic spell, something called the "Vestige of the Lost". However, even the boss cannot control the full spell and has to split it into three components which it channels through orbiting altar-like enemies. To defeat the boss, Boki has to [[PowerCopying copy all three component powers]] ([[spoiler:Underworld Fire, Accursed Claw and Profane Edict]]) and and then combine them to unleash the spell's full power. [[RealityBreakingParadox The result is not pretty]], though fortunately this all happens in a simulation, so the worst that happens is the sim crashes and Boki gets knocked out.
471** Boki can use Vestige of the Lost again in Pandemonium Mode. It will destroy every enemy in its path, but it will also hurt Boki and leave her with only 1 HP and no powers other than her Boki Beam.
472* In ''VideoGame/DarkestDungeon'', the Jester class can learn a move called Finale that deals tremendous damage to a single target, that can be buffed even further by using the other moves in the jester’s arsenal (With special mention going to Solo which grants huge buffs to finale while also giving the jester the marked status effect and throwing them into the first position, where finale can only be used.) The catch? Using this move inflicts heavy speed, dodge and stress debuffs on the jester, ensuring that if the fight isn’t already over, the jester will certainly be out of it, and much more likely to be killed or driven mad by anything left standing.
473* Chapter 2 of ''VideoGame/{{Deltarune}}'' has an alternate story route known as the [[spoiler:[[CorruptTheCutie Weird/Snowgrave Route]]]], where [[spoiler:[[TheCorruptible Noelle]]]] learns a spell called [[spoiler:[[OneHitKill Snowgrave]], which can only be used with the [[CastFromHitPoints Thorn Ring]] equipped.]] If used during the fight where it is first learned, it can only be used once, as [[spoiler:Noelle leaves the party afterwards due to [[MyGodWhatHaveIDone realising what she has just done]].]]
474* In the background lore for ''VideoGame/DiabloIII'', the Wizard character is doing this when [[FeaturelessProtagonist they]] expand their arsenal to include [[PureEnergy the manipulation of raw mana]] and [[TimeMaster controlling time]], as well as when they ignore the normal rules about EquivalentExchange that other casters adhere to in order to prevent magical fallout or corruption. This is why the Wizard is much more destructive than the Sorcerers of the past two games.
475* Source magic in the ''VideoGame/DivinityOriginalSin'' series is treated as this. In the first game, it was corrupted and subject to WithGreatPowerComesGreatInsanity, with most of its users going insane and evil the further they delve into Sourcery. In ''VideoGame/DivinityOriginalSinII'' this is no longer the case, but instead Source attracts otherworldly monsters known as Voidwoken and anyone found using it is slapped with an AntiMagic collar and hauled off to an internment camp.
476* A few heroes in ''VideoGame/Dota2'' have abilities that are like this. Some examples are Huskar's ''Life Break'', an ability that will deal 35% of an enemy's current HP as damage, but will do the same thing to Huskar himself, and the Techies ''Suicide Squad, Attack!'', which will kill the Techies with a massive explosion, but will also deal massive damage to any enemies in the explosion's radius, if not kill them outright.
477* BloodMagic is treated as this by most factions in ''Franchise/DragonAge''. It is ''extremely'' powerful and dangerous -- [[BloodyMurder to]] [[MindControl enemies]], [[PoweredByAForsakenChild allies]], [[CastFromHitPoints and the user]] -- and is forbidden virtually everywhere outside Tevinter. While in theory, it's no more dangerous than regular magic, the potential for sacrificing or controlling others is considered too dangerous by almost everyone. Even the Tevinter Imperium officially condemns BloodMagic, though in practice all of the Magisters are secretly Blood Mages. The [[WellIntentionedExtremist Grey Wardens]] don't officially forbid it, but many are still leery of it.
478* The ''Franchise/DragonQuest'' games have two such spells. One is Kamikazee, which has a near guaranteed chance of utterly destroying anything that isn't a boss. The other is Kerplunk, which revives the entire party and restores them to full health. Both of these spells will kill the user.
479* ''VideoGame/DungeonCrawl'' has a lot of examples.
480** Lugonu's self-banish causes permanent damage to HP and MP.
481** As does Borgnjor's Revivification.
482** Most necromancy is partially cast from HP.
483** High-level summonings can break free and turn hostile at random, and those that can't will instead inflict nasty stuff like sickness and intelligence loss on the caster.
484** Downplayed with mid-level summonings, most of which have a chance to be hostile.
485* ''Franchise/TheElderScrolls'':
486** Redguard warriors known as "Sword Singers" could become so skilled with their blades that they were said to be able to [[FantasticNuke split atoms]] using a technique known as the "Pankratosword." It is said that their original homeland of Yokuda was destroyed by this technique, so it became forbidden and was lost to history. (Though the "destruction of the homeland" story is hinted at being an embellishment, and the Redguard people left Yokuda to escape much more traditional violence and oppression.) This being ''The Elder Scrolls'', where lore is often intentionally contradictory, it is left up to the audience to draw their own conclusions.
487** The Bosmer have a technique known as the Wild Hunt where they call upon the power of their patron god to turn into horrifying, berserk creatures that kill and consume everything in their path. However, the transformation is permanent and changed Bosmer are so consumed by their hunger that they will literally eat ''each other'' if no prey is readily within reach, meaning that Wild Hunts usually end with a "cannibalistic orgy" (as described by one InUniverse writer) once the affected Bosmer kill and consume every other animal or person they can find. Bosmer are ''deeply'' ashamed of using the Wild Hunt, to the point that it is only used in the most [[GodzillaThreshold dire of circumstances]] and there are only two documented instances of it happening in recent Tamriellic history; to its credit, however, both uses achieved the desired goals.
488* ''VideoGame/EternalTwilight'': The setting features many varieties of magic, but Blood Magic is the most powerful in offense and manipulating life. However, using it causes one's sanity to erode and the soul to be tainted.
489* In each of ''VideoGame/EYEDivineCybermancy'''s [[MultipleEndings three main endings]], you are rewarded with a unique and hyper-lethal "Gate" psychic ability. The Hypnotic Gate instantly and permanently paralyzes an enemy, Triangular Gate warps an enemy out of reality, and Substitution [[LifeDrain causes the player to be healed if the enemy takes damage]], and damage the enemy if the player is hurt. All of the abilities are also hyper-lethal for the ''user'', as they have a very high probability to fling the user towards random directions at lethal speeds, [[WithGreatPowerComesGreatInsanity drive them insane]], fry their brains, or cause [[ScarsAreForever permanent trauma]] which hurts stats and persist even after resurrector usage.
490* ''Franchise/FinalFantasy'':
491** ''VideoGame/FinalFantasyIV'':
492*** The sage Tellah is seeking the ultimate magic spell, Meteo(r), so that he can seek revenge on Golbez (the game's BigBad) for the death of his daughter Anna. Sure enough, Tellah eventually learns the spell from his [[ForgottenSuperweapon repressed memory]], and uses it against Golbez, killing himself in the process. Other, more youthful mages, as well as an eternal precursor, can cast it without side effects. In gameplay terms, this means that he never ends up getting the required amount of MP to cast it.
493*** In the DS remake, thanks to the NewGamePlus mode the game has, you can easily subvert this: while the items to raise your max MP wouldn't normally be accessible until after his death, they can be carried over from your previous playthrough and indeed, using one on Tellah will allow him to cast Meteor as many times as you want with no ill effects.
494** In ''VideoGame/FinalFantasyThe4HeroesOfLight'', the Crystal puts an ominous pause into its usual new-crown recitation by saying "To thee, I give this gift of light, upon thy head a crown of... forbidden might" when you get the final one, Dark Fencer. The Desolator spell obtained at the same time is treated in the same way.
495** ''VideoGame/FinalFantasyXIV'':
496*** Louisoix uses a powerful imprisoning spell that is fueled by the aetheric power of numerous prayers in an attempt to rebind the Primal Bahamut before he causes more damage throughout Eorzea. However, the spell is so powerful, it drains every last ounce of aether within the caster using it and while Louisoix didn't use the spell fully as Bahamut broke free, it was enough to end his life as he stopped Bahamut. [[spoiler:Papalymo, one of the Scions of the Seventh Dawn, does this to seal away a brand new Primal temporarily, dying in the process. It ends up being a SenselessSacrifice since the new Primal, Shinryu, ends up escaping anyway to the point that [[GodzillaThreshold Omega]] has to be used.]]
497*** In the game's lore, White and Black Magic are treated as this. The overuse of both schools of magic during the War of the Magi led to the Sixth Umbral Calamity, seriously draining the planet of its aether in the process. As such, both White and Black Magic are considered forbidden arts under Eorzean law, with very few exceptions ever allowed. The Padjal of the Black Shroud can safely use White Magic, since they are keyed into the elementals, and any who practice White Magic without their blessing is considered an outlaw. Black Magic, meanwhile, is outright banned because those who practice it often cause widespread death in their wake, with the PlayerCharacter being given a pass because they are [[TheHero the Warrior of Light]]. The disastrous results of the abuse of White and Black Magic also gave way to [[TheRedMage Red Magic]], which is a more {{Downplayed}} take on this trope: instead of drawing aether from the planet, Red Magic [[CastFromLifespan uses the aether in the caster's body]]. Overuse of Red Magic won't endanger the planet, but it can imperil the user's life, hence the Red Mage's use of special crystals to amplify the effects of smaller amounts of aether.
498*** Y'Shtola has this with the Flow spell. [[spoiler:It's a dangerous teleportation spell where the user and anyone caught in it is scattered into the aether. It's not until midway through ''Heavensward'' that she's returned from it, but now having ProphetEyes. Thancred ended up NakedOnArrival in the Dravanian Forelands, though now he can no longer use even the basic spells like Teleport or Return, rendering him an utter muggle. Minfillia ran into the Flow spell so she could become one with Hydaleyn. The second time she used it was in ''Shadowbringers'' to escape Vauthry's [[TheDragon general]], Ran'jit, and it was only thanks to Emet-Selch pulling her out of the aether this time that a crisis was averted.]]
499*** The Ruby Weapon in ''Shadowbringers'' has "Oversoul". [[spoiler:When activated, Oversoul grants the Ruby Weapon a power boost on the scale of a primal, but at terrible cost: the pilot is absorbed into the Weapon's core and forcibly transformed into a clone of whoever's fighting data is in the Weapon's data banks -- in the case of the Ruby Weapon, Nael van Darnus. And what's worse... the pilot was one of [[HeelFaceTurn Gaius Belsar's]] [[OutlivingOnesOffspring adopted children.]]]] Throughout the ''Sorrow of Werlyt'' storyline, the pilots of the Weapons know that [[spoiler:piloting one win or lose is a suicide mission against the Warrior of Light, especially since the pilots are Gaius Belsar's adopted sons and daughters.]]
500*** In gameplay, there are the invincibility abilities used by the Dark Knight and Gunbreaker tank jobs, "Living Dead" and "Superbolide" (respectively). "Living Dead" allows a Dark Knight to survive otherwise fatal damage with just 1 HP while granting them invulnerability, but if their HP is not completely recovered within ten seconds of entering this "Walking Dead" state, they will die automatically. "Superbolide", meanwhile, grants immediate invincibility for eight seconds, albeit at the cost of reducing their HPTo1, leaving them in a very vulnerable state if they cannot get healed quickly.
501* An antagonist example: In ''VideoGame/GoldenSun1'', shapeshifting into dragons seems to be a Dangerous Forbidden Technique of the Mars Clan of Prox, requiring a great deal of energy and completely wiping out the user's abilities afterward. Saturos even warns Felix in the first game that he and Menardi won't be much help after fighting Isaac & Co. as the Fusion Dragon (which they aren't, though [[DoomedByCanon not for the reasons Saturos had expected]]). [[spoiler:When it's {{forced|Transformation}} on the antagonists of ''VideoGame/GoldenSunTheLostAge'', they are left without enough power to warm themselves against the freezing cold of the Northern Reaches, and freeze to death. And then the Wise One forces the transformation on ''[[PlayerPunch your parents]]''...]]
502* The first four ''[[Franchise/DotHack .hack//]]'' games feature Data Drain, a technique that allows the user to either severely weaken a computer-controlled enemy, or MindRape a human being (most humans hit with a Data Drain end up in comas). The hero, Kite, is the only human with the ability. He uses it to weaken game enemies that have been hacked so as to have infinite HP, thereby making them easy to defeat and to gather virus data to hack into protected areas of the game. The catch is that repeated use will corrupt his character data with the virus, causing nasty side effects in battle and, eventually, his character's death.
503* ''VideoGame/{{Ikaruga}}'': "Release the restraint device. Using the released power may result in [[ExplosiveOverclocking destruction of the ship]]".
504* ''Franchise/KingdomHearts'':
505** Channeling the darkness is this for most characters. Riku and Terra pay heavy prices for its uncontrolled usage, [[spoiler:getting them both possessed by the BigBad in the first ''Kingdom Hearts'' game and ''Birth By Sleep'', respectively.]] However, in the sequels, [[spoiler:Riku manages to tame the power.]]
506** In addition, many of the ''Kingdom Hearts'' villains themselves cannot control the darkness, with some such as [[WesternAnimation/{{Cinderella}} the Tremaine family]] and [[WesternAnimation/Frozen2013 Hans]] paying the [[EvilMakesYouMonstrous ultimate price]] for using it. Maleficent actually appears to Hades and cautions him not to delve too deep at one point in the story. [[spoiler:Ironically, she delves too deep and is slain at the hands of Sora and company (though it should be noted that she had her heart forcibly opened to the darkness by Ansem; she follows her own advice). Hades, while defeated in the Hades Cup, does not die, being a god, and reappears in ''Kingdom Hearts II'' not at all worse for wear.]]
507** The spell Zettaflare shows up, the most powerful BlackMagic spell in Creator/SquareEnix history. Previously in ''VideoGame/BravelyDefault'', it had only ever been used by a FinalBoss being fueled by the power of an evil butterfly. [[BewareTheSillyOnes Donald Duck can cast it on a spur of the moment]] at the cost of using nearly all of his life force and knocking himself unconscious for a while. Goofy's line beforehand seems to indicate that he's done this before.
508* Zed in ''VideoGame/LeagueOfLegends'' is stated to have learned forbidden shadow techniques to defeat his rival Shen, and become a more powerful ninja. It mostly translates to throwing living shadows everywhere.
509* In ''VideoGame/TheLegendOfZeldaTearsOfTheKingdom'', one such technique comes up twice: [[spoiler:By swallowing a Secret Stone, one is capable of transforming into a mighty dragon. In this form, one becomes effectively immortal, but [[DeathOfPersonality completely lose their sense of self]]. Ganondorf does this at the end of the game, becoming a Demon Dragon at the cost of his sanity and soul simply so he can defeat Link. Before this, Zelda -- at the time, displaced in the past -- swallows her Secret Stone to become a Light Dragon, sacrificing herself as part of a plan to restore the Master Sword after Ganondorf damaged it so Link can use it to defeat the Demon King. Thankfully for Zelda, the spirits of Rauru and Sonia are able to reverse the transformation and restore her body and soul after Ganondorf is vanquished.]]
510* In ''[[VideoGame/LivePowerfulProBaseball MLB Power Pros]]'', Alvin has a special pitch, the Mirage Knuckler, but it is extremely dangerous to try to catch it, so much after Alvin and Mark, [[GeniusBruiser the catcher]] train with it for a week, Mark is covered with bruises.
511* ''VideoGame/MegaManBattleNetwork'':
512** In those games, the Dark Chips are extremely powerful, but that permanently reduce your max HP by 1 with each use. Also, each use drops your KarmaMeter, and enough uses will disable Soul Unisons.
513** ''Battle Network 5'' also has Chaos Soul Unisons, which allows you to use a Dark Chip as your charged shot for one round of battle without any of the permanent negative side effects. However, there is a noticeable chance ([[GameBreaker game-breaking glitch]] notwithstanding) that the charged shot will fail and backfire, instead summoning an invincible shadow copy of Mega Man to join the enemies and attempt to beat the crap out of you. Also doubles as DifficultButAwesome, as enough use of Chaos Unison trains the player to be able to use it multiple times in succession without being knocked out of it without PauseScumming, meaning the player can continue charging even if they're being pressed. Shadow Chaos, Knight Chaos, and Magnet Chaos are particularly deadly upon being mastered.
514* In ''VideoGame/NetHack'', one can choose to break a magic wand in half, unleashing all the remaining power at once. Can be dangerous as most wands will simply explode.
515* ''VideoGame/OdinSphere'' has Oswald's shadow form. In gameplay terms, it vastly increases his attack speed and power, at the cost of rapidly eating away as his POW meter (which, if depleted, causes him to become exhausted and unable to move or attack until it refills completely.) In story terms, using it too much will destroy Oswald's soul and turn him into one of the ghostly Revenants haunting Winterhorn Ridge [[spoiler:which eventually does happen in one of the bad ending scenarios, is Oswald is pitted against Onyx.]]
516** There's also the Darkova spell, which transforms the user into a massive, powerful Cerberus. The former king of Titania used it once to try and fend off enemy forces and went mad with power, ravaging Titania for seven days until he was finally slain by his son. [[spoiler:Ingway finds out how to use it, and it similarly comes back to bite him as soon as he does.]]
517* In the ''VideoGame/PhantasyStar'' series, Megid invokes this trope by name. In [[VideoGame/PhantasyStarII PS2]], it's CastFromHitPoints at a painful rate. In ''VideoGame/PhantasyStarIII'' it's only invoked in a cutscene, but when it is, ''it wipes out an entire city in a single casting.'' Note that [=PS3=]'s setting is largely medieval compared to the sci-fi ambiance of the rest of the series, so any spell capable of leveling a city is pretty much the equivalent of the Tsar Bomba. In [[VideoGame/PhantasyStarIV PS4]], the negative effects on the player are gone, potentially due to where it comes from and what the stakes are at the time, but it's not easy to access (being guarded by a [[SealedGoodInACan Sealed]] GoodIsNotNice [[SealedGoodInACan in a Can]] guardian who you need to outwit to get it) and the only other user of the spell is the EldritchAbomination that threatens to wipe out the entire star system (and, ostensibly, the universe after that) if you fail in your quest.
518* Multiple moves in the ''Franchise/{{Pokemon}}'' franchise harm the user, but these moves also tend to be very powerful.
519** [[SuicideAttack Self-Destruct and Explosion]] faint their user, but cause ''tremendous'' amount of damage to their foes (200, 250). They're two of the most destructive moves in the whole series, surpassing almost all powered-up moves.
520** Misty Explosion, introduced in [[VideoGame/PokemonXAndY Gen VI]], works the same as Self-Destruct and Explosion, but has a base power of 100. However, if their user is grounded on Misty Terrain, the base power raises up to 150.
521** Struggle is the "last resource" move, only used when the PP of all previous moves have been emptied. It's a rather weak move that damages the user by 1/4th of its max HP. Chances are, you're only using it four times before you die. And that's a base case scenario; considering that it's a move that only becomes available when all your other moves are out of PP, odds are it'll do even less than that.
522** Focus Punch is extremely powerful but takes one turn to power up, leaving the user open for attack, and if the user is hit while powering up, it "loses focus" and can't attack.
523** Hyper Beam and all of its variations have a base power of 150, but renders the user immobile on the next turn.
524** Curse (if used by a Ghost type) sacrifices half its total HP in order to have the foe lose 1/4 HP every turn. If used when the user has less than half HP left, they faint.
525** Belly Drum is similar to Ghost!Curse, but the HP sacrifice is done to maximize the Attack stat, instead, and fails when its user is at half HP or less.
526** Final Gambit, introduced in [[VideoGame/PokemonBlackAndWhite Generation V]], causes the user to deal its current HP to the enemy at the cost of fainting.
527** Overheat and Close Combat are quite powerful, but cause Stat drops to the user and leave them vulnerable to opposing attacks.
528* ''Franchise/SonicTheHedgehog'':
529** Similar to his anime counterpart, Shadow the Hedgehog can gain an extreme power boost whenever he removes the bracelets from his arms. Unlike the ''Anime/SonicX'' version, however, it doesn't appear to drastically drain his energy. He only used this power once in ''VideoGame/SonicTheHedgehog2006'' to save himself, Rouge and Omega from [[BigBad Mephiles the Dark]], who used two of the Chaos Emeralds to create an army of clones of himself.
530** Although not typically portrayed as such, [[GoldenSuperMode Super transformations]] can be this, ESPECIALLY for those who aren't experienced with it. It grants the user invincibility, immeasurable physical and magical enhancement, and the power of flight, but it's also tied directly to how many rings the character has on hand. If they burn through their rings, they de-transform and, [[AstralFinale due to the]] [[AmazingTechnicolorBattlefield situations in which]] [[FinalBossNewDimension the form is typically used]], they're pretty much dead. Even when the environment doesn't present an immediate risk, using too much energy at once not only bleeds through the character's stock of rings insanely fast but leaves them on the brink of exhaustion before they even get the chance to de-transform. [[VideoGame/SonicAdventure2 Shadow]] [[VideoGame/SonicUnleashed and Sonic]] have both experienced this and almost died anyway after neutralizing the threat at hand. Furthermore, characters such as [[KidHero Tails]] and [[EvilKnockoff Mecha Sonic]] are so inexperienced with Chaos power that they need not only the Chaos Emeralds but a secondary source ([[VideoGame/Sonic3AndKnuckles In Tails' case, the Super Emeralds and in Mecha's case, the Master Emerald]]) to even transform in the first place.
531* ''VideoGame/{{Stellaris}}'': There are some really special technology pathways which if researched grant your star empire some exceptionally powerful bonuses but could also have potentially disastrous consequences for the entire galaxy. Playing with [[PsychicPowers psionics]], for instance, can net you {{Exp|y}}ies of [[Franchise/StarWars Jedi]] and [[TabletopGame/Warhammer40000 Navigators]], as well as upgraded versions of the best starship drive in the entire game, but [[spoiler:may also lead to an invasion by very hungry EnergyBeings from another dimension]]. Pursuing the development of robots and AI can lead to pops that can survive on any planet, aren't affected by happiness ratings and have increased production of every resource, but will push for synthetic civil rights as you climb up the SlidingScaleOfRobotIntelligence and you can even [[spoiler:end up with a RobotWar if you have too many disenfranchised synthetics in your empire]].
532* The ''Satsui no Hadou'' ("Surge of Murderous Intent") from ''Franchise/StreetFighter''; a dark ki that fighters seeking victory and power can call upon should they be willing to fight without mercy. Gouken hated this aspect of his fighting style and created a fork that does away with it in order to promote humanity and personal growth through martial arts. Despite that, Ryu constantly struggles to avoid succumbing (the endgame being the "what if" character Evil Ryu) and Gouken's brother Akuma has embraced it, despising Gouken for teaching a "softened" art (though he is not entirely in control of it, as Oni demonstrates can happen if he relies on it too much). Techniques that draw upon the ''Satsui no Hadou'' are themselves Dangerous Forbidden Techniques; being the Metsu Hadoken, Metsu Shoryuken, and Shun Goku Satsu (the last one potentially being lethal to both the victim and user, depending on the contents of the user's soul).
533* ''VideoGame/SuikodenIV'' offers us the Rune of Punishment, which drains the user's life every time it's used. The rune itself is sentient and tries to engineer events around it to guarantee it will keep getting used, until eventually its bearer is killed and the rune jumps to a new host, only to begin the cycle anew. Interestingly, the Rune of Punishment governs atonement and forgiveness. [[spoiler:if the player is able to forgive the resident backstabbing friend Snowe throughout the course of the game (and he becomes less and less worthy of forgiveness as time goes on, so it's tough) and recruit all 108 Stars of Destiny, Leknaat appears and says that the rune's time of punishment is at an end, and the time for forgiveness has arrived. In addition to unlocking the most powerful rune attack, which greatly damages enemies and greatly heals allies, the improved Rune of Punishment no longer injuries the user for attacks.]] This, of course, implies that everyone that used the rune before was either a) stupid and greedy, or b) unable to understand the proper implications of forgiveness. Compare the Soul Eater Rune in the first ''VideoGame/{{Suikoden|I}}'' game, which... [[ExactlyWhatItSaysOnTheTin eats souls]].
534* The Hell Stringer Technique of the Orphes in ''VideoGame/SuperRobotWarsUX'' is basically a combination attack with the Lyrath that uses the Lepton Vector Engine. Richard uses it to bend the space-time continuum, so he could survive. Richard's body was already screwed up by then and that use pretty much was the final nail.
535* ''VideoGame/TeamFortress2'': While there are many weapon choices that take away a Class's health, or impair them in some way, to allow for more options in stat bonuses (such as melee weapons Sandman, the Eyelander, and the Conniver's Kunai all taking away base health), the only weapon that truly fits this description is the Equalizer and its brother the Escape Plan - specifically, their tauntkills, the Kamikaze. Other tauntkills are just choreographed one-shot-kill techniques that require precise timing, luck, or an idle enemy to succeed in hitting, as they're either in melee range or a very thin line forward (the Heavy's Showdown taunt). The Kamikaze is not just long-winded and choreographed, it also kills the player that performs it - Soldier grabs his chest frag grenades, pulls one's pin, and forces it to explode.
536** However, it can be choreographed even further/made more difficult to use - Simply equip the [[https://tvtropes.org/pmwiki/pmwiki.php/VideoGame/Worms Lumbricus Lid]] cosmetic. With it equipped, perfforming the taunt will also play the "Hallelujah" section of Hendal's Messiah, and a [[AndYourRewardIsClothes unique killfeed icon]] that depicts the Holy Hand Grenade.
537* ''VideoGame/{{Tenchu}}'': In Wrath of Heaven and its Xbox port Return from Darkness, Rikimaru and Ayame are able to learn a technique based off the original game's title "Wrath of Heaven", though the technique slightly differs between the two as Rikimaru can only target one enemy who is instantly killed if struck, even boss characters; Ayame on the other hand simply damages all enemies near her in a giant energy thrust. The one thing this technique has in common with both is that using it reduces your HP to 1 point, so you have to be sure you hit your target(s), otherwise you will be left open to an enemy attack that will all but kill you if you don't have a Ninja Rebirth on hand or can't down a Health Potion quickly enough.
538* In ''VideoGame/TraumaCenter: Under the Knife'' Derek's senior surgeon forbids him from using the [[BulletTime Healing Touch]] after his first intentional use of it makes him collapse after the operation... with the caveat he's completely aware Derek will merrily ignore this instruction if he thinks the Healing Touch will mean the difference between life and death. This is meant to communicate to the player that they should only use it as a last resort, as doing so will negatively impact their score. [[GuideDangIt Good luck figuring that out without trial and error, though.]] Although the only time that the Healing Touch is actually bad is in ''Under the Knife'', where it slaughters your ranking. Any game from ''Second Opinion'' or later have no penalties to using the Healing Touch.
539* In ''VideoGame/UltimateAdmiralAgeOfSail'', the merchant ships which you mainly use as troop transports can be upgraded and converted into Fire Ships. When used in this manner, they're filled with oil and rags, sailed close to an enemy ship, [[KillItWithFire ignited]], and [[SuicideMission then the crew attempts to bail out]]. Doing this can allow you take out ships [[DavidVersusGoliath much more powerful than your own]]... but you'll be expending a whole ship to do it, the merchant ships aren't very fast so it takes luck to catch a warship, and the fire will spread to anything that gets too close, [[HoistByHisOwnPetard regardless of whose flag it's flying]]. This tactic was [[TruthInTelevision actually used in real life]] during [[WoodenShipsAndIronMen the Age of Sail]], usually against groups of anchored ships at night.
540* ''VideoGame/{{Utawarerumono}}'': Kuon in the sequels has her divine blood. As she is the daughter of Uistalnemetia's human host, she has access to the god's powers and is theoretically capable of a level of power surpassing even the BigBad. However, every time she uses even a small amount of it, it leaves her utterly exhausted and feverish, and when she does try to use it in full, [[spoiler:it's far too much for a mortal spirit to handle, and she winds up being possessed by Uistalnemetia's dark side. At that point the rest of the heroes require a literal DeusExMachina to save her.]]
541* ''VideoGame/VagrantStory'' has learned techniques that, when used, [[CastFromHitPoints drain a portion of your health]].
542* In ''VideoGame/ValkyriaChronicles'', Valkyrur are already so powerful that not only can they fire huge lasers, NORMAL BULLETS HAVE NO EFFECT ON THEM AND MORTAR ROUNDS CAN ONLY STUN THEM. However, they can sacrifice their life to do things on the scale of annihilating a fort, and the army inside it in a giant blue flame.
543* ''VideoGame/ValkyrieProfileCovenantOfThePlume'' has a [[PlayerPunch heartbreaking]] example in the Destiny Plume. Left by Lenneth on Wylfred's father's body and corrupted by the goddess Hel, it can make any unit absurdly powerful - ten times as powerful in every single stat. And at the end of the stage, they die. Wyl is forced to use its power on his best friend and would-be {{Lancer}} at the beginning of the game...
544** Exactly how forbidden to make it is left up to the player, though, and [[MultipleEndings affects the outcome of the plot.]]
545* Familiars of Witches in the world of ''VideoGame/{{Wadanohara}}'' have an ability like this, giving them a massive power boost after [[BloodMagic drinking their witch's blood]], however abusing the power is stated that it will kill the Familiar. This is first demonstrated by Chlomaki having Lobco to kill a huge amount of Tosatsu kingdom warriors in one go. It is later used [[spoiler:in the true ending, when Samekichi needs to [[HeroicSacrifice go into the Sea of Death to close the gate]] and can't be certain that he will make it with his own power. Wadanohara has been stabbed already, so he takes some of her blood so that he will be strong enough to do his mission.]]
546* ''VideoGame/TheWorldEndsWithYou'':
547** Joshua uses his [[spoiler:[[BeamSpam Jesus Beam]] attacks to get himself and Neku out of a battle with a Taboo Noise. Though not dangerous in itself, he held back this power until this moment to conceal his identity as the [[{{God}} Composer]], and used this power in the sight of a Reaper, thereby drawing suspicion to himself.]]
548** Late in the story, Kitaniji orders all the Reapers to wear special "O-Pins", which Uzuki gleefully describes as granting "unchained power". Kariya points out that there's probably a good reason the chains are normally kept on. [[spoiler:Subverted; as Konishi managed to figure out, Kitaniji ''lied'' about what they do. There's no power boost at all, they're just part of his AssimilationPlot.]]
549** [[spoiler:Hanekoma]] decides to [[spoiler:revive [[WildCard Minamimoto]] as a Taboo Noise]] to interfere with the BigBad. He reveals this himself to the player in the [[spoiler:[[UnreliableNarrator secret reports]]; while not really dangerous to himself, the action drew lots of unwanted attention from his fellow Angels]].
550* Some Techniques and Spells in ''VideoGame/RomancingSaGa'' drain LifeEnergy if one is low leveled in That field of magic or if the weapon uses LifeEnergy for its techniques.
551* In ''Videogame/XenobladeChronicles2,'' there exists a [[BackgroundMagicField Background Magic Field]] called Ether, which also exists in all living creatures. Humans cannot normally access this power, but [[EmpathicWeapon Blades]] can absorb it from the air, then transfer it to their human partners. When the Party meets an enemy who tampers with the ether in the air, preventing their blades from absorbing it, [[spoiler:Vandham]] impales themselves with their own Blade Weapon, using the ether in their own body to power their attacks. [[spoiler:[[HeroicSacrifice He doesn't survive it]]]]
552* Played for laughs in ''VideoGame/YakuzaLikeADragon:'' There is a side quest in which our hero Kasuga can invest in a giant street-cleaning Roomba. When the inventor demonstrates it, he turns on the "forbidden high power mode," the Roomba starts sucking in cats and old ladies, and you have to fight it.
553* ''VideoGame/ZenoClash'': The "[[ExactlyWhatItSaysOnTheTin Trick with the Bomb]]". It's simple: the user takes out a skull bomb, pulls the pin, and holds it up to their attacker's body, letting the blast take them both. Ghat [[SuperToughness can survive this]], though it's extremely painful. Most of his enemies can't.
554* In ''VideoGame/ZettaiHeroProject'' Dangerama's entire skillset is composed of these. As a DeathSeeker, this makes sense.
555[[/folder]]
556
557[[folder:Visual Novels]]
558* In the Fate scenario of ''VisualNovel/FateStayNight'', Saber comes under this limitation because using her Noble Phantasm requires all the mana she's currently holding to activate (and her flawed summoning means Shirou can't provide her with any), and she ends up facing at least three enemies that require -- or at least seem to require -- the use of it to defeat.
559** In Heaven's Feel, projection [[spoiler:(more specifically, projection using Archer's arm)]] becomes this for Shirou. While it puts a strain on him in all three paths, this path specifically gives him a clear limit on usage, and overuse will kill him. [[spoiler:Which it eventually does.]]
560** Furthermore, each Servant has a power known as the Broken Phantasm -- willingly breaking their Noble Phantasm. This renders the servant without their proof of heroism (which for many of them is their weapon) but also inflicts massive one-time damage on whoever the Phantasm is shattered on. [[spoiler:Archer, who can create Noble Phantasm duplicates, routinely uses this technique to compensate for the fact that his duplicates are weaker than the real thing.]]
561* The protagonist of ''VisualNovel/{{Tsukihime}}'' has the Mystic Eyes of Death Perception, which allow him to see the concept of death itself on ''everything'' in the form of lines and points. Observing death, however, will lead to insanity, so he has to use special glasses which block his ability. Every time he takes off these glasses his eyes get stronger, but since humans are not meant to observe the nature of death it puts an increasingly enormous strain on him. In fact, in the [[spoiler:epilogue, which takes place a while after any of the routes, it is revealed in his reunion with his 'sensei' that he is literally on the verge of death, in part due to his ability; it is heavily implied that he actually dies just after they part ways.]]
562[[/folder]]
563
564[[folder:Web Comics]]
565* ''Webcomic/EightBitTheater'':
566** '''HADOKEN!!!!''' Although not considered forbidden, Black Mage is only able to cast that spell once a day, and it makes a cute little [[NukeEm nuke-sized]] crater wherever he aims it.
567** Spells that drain the net amount of love from the universe with each use and require the sacrifice of orphans to gain in the first place tend to have a bit of a social stigma against them. Black Mage seems to find an excuse to use it nearly every day...but then again, this is Black Mage.
568** Also, the Ice-9 spell, which was purely theoretical until Red Mage used it to defeat Kary, the Fiend of Flames. No one had ever cast it up to that point because it would put ''everything in existence'' on ice. Thankfully, RM had a BagOfHolding which contained both Kary and the spell.
569* Illusion magic in ''Webcomic/AnotherGamingComic''. In the group's backstory, the use and abuse of illusion magic had reached the point where the players were forced in simple self-defense to specifically and explicitly test ''every single thing'' they encountered to confirm that it wasn't an illusion, slowing the game to a snail's pace and driving the GM to dangerous levels of fury. In the end, the problem was only stopped by the signing of The Treaty, an actual real-life, notarized treaty that banned the use of all forms of illusion.
570* The Forbidden Move in ''Webcomic/AxeCop Gets Married'': When Axe Cop's opponents at a fighting restaurant in China do a secret move that combines them all into a giant fighter, Axe Cop counters that he knows a move that is ''more'' than secret -- meaning because it's forbidden. The technique has not been explained as forbidden before, but everyone knows about it and panics when he starts to do it because it will kill everyone in two provinces. The move creates a giant tornado that picks up the adjacent province and smashes your opponent with it. Ultimately {{subverted}}: Axe Cop shows that when done ''correctly'', the move only affects the one opponent, removing everyone and everything else to safety and then putting them back too fast for anyone to notice.
571* Jacob from ''Webcomic/DemonFist'' can [[spoiler:teleport]], but doing so damages his body. Using the power to escape with the ''[[CoolShip Hookshot]]'' was what cost him his hand.
572* In ''Webcomic/ElGoonishShive'', magic apparently drain users at various rates. Spells too powerful to handle may overtax even well-trained magic users, possibly even [[BroughtDownToNormal removing their magic for months at a time.]]
573* The Shield of Wonders from ''Webcomic/{{Goblins}}'' is an ArtifactOfDoom that casts random magical effects when struck. Simply using the Shield in combat is a Dangerous Forbidden Technique since it's barely less dangerous to the user than it is to his enemies. [[spoiler:Naturally, Complains is forced to use it profusely in a DeathOrGloryAttack, and naturally the shield almost kills him a couple of times and turns him into a half-demon.]]
574* In ''Webcomic/{{Heartcore}}'', we have Blast Bomb, Volaster's most powerful spell: upon letting himself be injured to the point where he is bleeding out rapidly, Volaster uses his salamander demon blood to turn himself into a FantasticNuke. In addition to killing himself in the blast, it also damages his Heartcore, which causes his offspring/successor, Carval, to suffer from stunted growth.
575* ''Webcomic/KillSixBillionDemons'' has entire SupernaturalMartialArts styles consisting of this.
576** The angel-only martial art Krayu Mat, a style intended for facing demons and gods. It is rarely used because of the immense physical and spiritual strain it requires, and any creature with a weak soul flame (like humans) trying to practice it would utterly annihilate their own body in the attempt. When an angel uses Krayu Mat while in the physical realm, the angel's ContainmentClothing begins to crack from the strain.
577** Ki Rata, a martial style so dangerous to oneself and others that for centuries it was only practiced by a group of monks for only one reason - so they'd be capable of killing anyone else who tried to use it. It requires absolute concentration and breath control to be maintained at all time, to the point that a lapse in concentration while using Ki Rata will literally tear the body asunder. [[spoiler:Ki Rata also has a forbidden technique called "Slayer of Immortals", which basically works [[CastFromHitPoints by opening all the body's energy channels and turning the user's own body into fuel for their Atum]]. While it provides an ''immense'' power boost while maintained, the technique is implied to be fatal to its user.]] Solomon David is its most prominent user, fitting his status as Demiurge of {{Pride}}; [[ControlFreak he'd accept nothing less than perfect control anyhow]]. [[spoiler: He survives unleashing Slayer of Immortals, but it withers his right arm to a husk, damages his breathing (so he can never use Ki Rata again), and renders himself mortal too.]]
578* ''Webcomic/LastRes0rt'': Jigsaw Forte's Zombie Mode, while not explicitly a Dangerous Forbidden Technique, effectively becomes this when you realize if she uses it ''at all'' while on camera, she's blown her personal {{Masquerade}} (which means if she doesn't die from using it in the first place, ''she will'' when she's done). WordOfGod implies that abusing the form does have plenty of consequences, but it depends on how she uses it/how much damage she sustains, not necessarily how often.
579* ''Webcomic/MSPaintAdventures'' and ''Webcomic/ProblemSleuth'' both feature '''SEPULCHRI-TUUUUUUUUUDE!!'''
580** [[ItMakesSenseInContext "No, you fool! Don't you realize if you initiate that attack, it will be the last thing you do??? Fiesta smacks some sense into you."]]
581* ''Webcomic/{{Unsounded}}'': "Core Leeching" is a purposely incomplete spell that causes the BackgroundMagicField of the Khert to see the target as "bad data" and erase it from existence. It's both illegal and terribly bad form because it has no tactical advantage over other spells, makes {{Magic Misfire}}s more likely in the area for a while afterward, and invariably causes a horrifically CruelAndUnusualDeath.
582[[/folder]]
583
584[[folder:Web Original]]
585* There are several different levels of it in the ''Literature/WhateleyUniverse''. Phase has a technique (using his disruption-light level on someone) that runs the risk of corrupting their Body Image Template if they are an Exemplar or Shifter, and turning them into something grotesque; he avoids it on moral grounds. Fey has some spells powerful enough that the energy drain will destroy entire ecosystems around her, which is way worse.
586[[/folder]]
587
588[[folder:Western Animation]]
589* ''WesternAnimation/{{Amphibia}}'': The GrandFinale reveals the "secret spell" of the three Calamity Gems; should one's power fall short, they can use all three stones to unlock an ultimate power that can destroy anything in one blow, but with the cost of literally exhausting and destroying the user's body, killing them after using it.
590-->'''Mother Olm:''' Summoning such power... '''comes at a price;''' the life of the user.
591* ''WesternAnimation/AvatarTheLastAirbender'' and ''WesternAnimation/TheLegendOfKorra'':
592** While it's not really forbidden, lightning redirection (a Firebending technique where you internalize lightning, either natural or created by another firebender, and shoot it in another direction) is extremely dangerous, to the point where even firebending masters are reluctant to teach it, because there's no real way to practice it first. First, you have to ''catch'' the lightning, which is just as dangerous as it sounds. While internalized, the lightning must be carefully controlled so it doesn't travel through vital organs. If the technique isn't performed ''perfectly'', then the user takes the full power of the lightning strike anyway, which is almost always fatal. By the end of the series, only three characters know the technique, and only [[OldMaster Iroh]] is skilled enough to avoid the dangers consistently. Zuko used it near the end of the show to [[spoiler:save Katara's life when Azula tried to kill her]], and ended up knocked unconscious.
593** Firebending was treated as this by Aang after he accidentally burned Katara with it due to fire's tendency to be uncontrollable at times. He never used firebending again until the last half of the final season, where he got much more extensive training in controlling it.
594** Bloodbending, supposedly the ultimate technique of waterbending, which involves moving around the blood in a living body and making that body do whatever you want it to do. Like the Osmosian example below, it is shown that it is detrimental to the Waterbender's sanity, making them AxCrazy and power-driven. To elaborate, Hama was bent on getting revenge after discovering the technique, Katara almost lost herself while trying to avenge her mother, in which she almost lost control while mercilessly bloodbending the Fire Nation's Guards. Unlike the first two, it's apparently quite easy to learn, at least for a master; it's mostly a matter of being willing to do it once you learn it's possible. Later on in ''WesternAnimation/TheLegendOfKorra'', it's revealed that bloodbending has since been outlawed completely and for good reason, as it turned out a mob boss learned the technique and used it to effortlessly control people whenever he liked. Even more disturbingly, this is also the source of [[spoiler:Amon's ability to remove someone's bending, via combining bloodbending with chi blocking]].
595** Energybending, a technique from before humanity first bent the elements, also carries the danger of mentally and spiritually destroying those who attempt to use it on others if their willpower isn't strong enough. [[spoiler:This nearly happened to Aang when he used it on Ozai.]]
596* A ''WesternAnimation/BatmanTheAnimatedSeries'' episode has a ninja steal a scroll in Japan that teaches him the secret of a "deadly touch" technique. When Batman faces him off in the end, he tries to avoid being touched by the guy in a specific spot, which (theoretically) would cause instant death. He fails and falls down, seemingly dead. He then gets up and knocks out the bad guy. When asked if the technique was bullshit, he pulls out a [[PocketProtector metal plate]] from under his suit, which has been deformed by a strong force.
597* ''Franchise/Ben10'':
598** The Omnitrix has the Master Control function, which disables the [[HourOfPower time limit for transformations]] as well as unlocking a variety of other features. However, going past the ten-minute time limit carries the risk of permanent damage to the user's DNA, although this seems to be more of an InformedFlaw as FutureBadass Ben 10,000 regularly ignored the time limit with no ill effects.
599** Osmosians are mutated humans that can absorb matter and create something out of that absorbed material (usually armor). They can also absorb energy, but it can turn them AxCrazy. This was initially used to explain Kevin being less villainous than in ''[[WesternAnimation/Ben10 the original series]] (he used to regularly absorb energy, but eventually stopped), but at one point Kevin has to absorb energy from [[spoiler:Ben's Ultimatrix to stop Aggregor's plans of taking [[RealityWarper a Celestialsapien's power]]]] in a last-ditch effort to prevent TheEndOfTheWorldAsWeKnowIt. [[spoiler:They defeated him alright, but afterward Kevin went as far as ruthlessly killing whatever comes his way in a rampage out of insanity.]] He was so insane his wrongdoings can be classified as NightmareFuel.
600* ''WesternAnimation/{{Chaotic}}'': For the [[LizardFolk Mipedian Tribe]], conjuring Warbeasts is this; a Warbeast is basically a [[PureMagicBeing Pure Magic]] {{Kaiju}} that can be summoned to devastate whole armies, but they're also wild animals with no conception of friend or foe, so the conjurer has to work ''really hard'' to maintain control of them. This lead to conjuring being outlawed by the Mipedian royals and the few conjureres who remained going into hiding. Come the M'arrillian invasion, however, this has changed; even the royals who outlawed it have become desperate enough to permit the Conjurers to return, even eventually having their own Warbeast bodyguard: Gaffat-Ra.
601* ''WesternAnimation/{{Cyberchase}}'': In "[[Recap/CyberchaseS5E6TheFlyingParallinis The Flying Parallinis]]", the Parallinis forbid themselves from tilting and leaning because the last time they used this ability, they saved Hacker and unknowingly released a villain into Cyberspace.
602-->'''The Parallinis:''' No tilting, no leaning, and no inbetweening!
603* In ''WesternAnimation/HeManAndTheMastersOfTheUniverse2002'' there was the Spell of Separation. Thousands of years before the present day, Hordak used it to divide Eternia into the Light and Dark Hemisphere's, hoping it would transform the Dark half into a realm where he could raise his dark army. But it was more powerful than he had thought and might have rent the entire planet in two if he hadn't realized it in time and put a stop to it. In the present day, Two-Badd gets ahold of the spell and believes it can be used to separate them back into their original forms of Tuvar and Baddhra; ignoring He-Man's warnings when he tries to stop them, they gather the three artifacts they need, and the spell is restarted where Hordak left off, forcing He-Man to push himself to his limits and return the three components before it literally destroys Eternia.
604* In ''WesternAnimation/JusticeLeague'' [[spoiler:the League had pretty much lost against the Brainiac/Luthor hybrid,]] until ComicBook/TheFlash saves the day by running at extreme speeds (to the point where he was circling the world in mere seconds) [[spoiler:and smacking Brainithor around by repeatedly running into him. Soon enough, he destroys all traces of Brainiac, leaving only a naked Luthor lying on the ground.]] However, in the process, he was almost swallowed by the Speed Force from moving so fast, and he says he probably won't be coming back if he ever goes that fast again.
605** In another episode, Flash and Luthor [[FreakyFridayFlip get their minds swapped]], and Luthor!Flash is able to run rings around the rest of the League on the Watchtower, in part because he's willing to use superspeed power tricks (such as vibrating objects enough to shatter them) that Flash normally avoids as too dangerous.
606* ''WesternAnimation/MiraculousLadybug:'' The Rabbit Miraculous allows its bearer to travel back in time and rewrite history, making it one of the single most powerful Miraculouses. The downside is... well, you're rewriting history. For this reason, the Rabbit is a "hero of last resort", only brought in [[GodzillaThreshold when all other heroes have failed]].
607** Since Tikki represents creation and Plagg represents destruction, combining the Ladybug and Chat Noir miraculouses is said to be able to allow the user to make literally ''anything'' happen - hence the BigBad's desire for them. However, Master Fu says that there is an equal and opposite reaction from doing this, so even the most well-intentioned attempt will come at a very high price. [[spoiler:The cost is that the wish will literally overwrite reality with a new one, essentially destroying everything and everyone from the old reality in the process.]]
608** The Miraculous have an effect on the body of the user, so there are circumstances under which even 'proper' use can be unsafe. The damaged Peacock Miraculous takes an increasing physical toll on its user and is implied to be the reason for Adrien's mother's coma. Also, when Marinette borrowed a large number of Miraculouses for one of her more complicated plans, she tries to take a step and nearly passes out ''even though they weren't active.''
609** The most dangerous technique of all: The Kwamis using their power on their own. It turns out that the human partners are {{Power Limiter}}s and the most impressive uses of the heroes' and villains' powers are a very small fraction of what the Kwamis can do - indeed, the Kwamis trying their ''hardest'' to hold back as much as they can when using their powers still generates much greater effects than the most extreme feats of the Miraculous' holders. On one occasion, Plagg creates an expanding wave of destruction that causes everything it touches to begin to tear itself apart. He tells Ladybug to use her WorldHealingWave in a hurry, suggesting that ''even he can't stop it. Now'' do you think Master Fu is exaggerating when he blames Plagg for ''[[PhlebotinumKilledTheDinosaurs wiping out the dinosaurs?]]''
610* ''WesternAnimation/{{Ninjago}}'': The Scrolls of Forbidden Spinjitzu from Season 11 make one's Spinjitzu more powerful but corrupt the user's personality as well. [[spoiler:It is one of these scrolls, combined with amnesia and Vex's manipulation, that causes Zane to become the tyrannical Ice Emperor for decades in the Never-Realm.]]
611* ''WesternAnimation/ReBoot'': Bob's fusion with Glitch is viewed as doing the unthinkable by Daemon's adviser, and Bob was fully aware that overusing his new Glitch powers would kill him. Bob comes very close to death when Daemon infects and forces him to overuse his powers to create portals. Bob does imply that the fusion would have been much less dangerous had Glitch not been damaged at the time (which is what necessitated the merger in the first place), however.
612* On ''WesternAnimation/RegularShow'', Muscle Man enters a bodybuilding contest, but since he doesn't have time to be fully fit, he concentrates on posing technique. As a last resort, he tries to execute a pose called the Shredder, which if done correctly, will "shred" the competition; but if done incorrectly, it causes the poser to ''explode''. [[spoiler:Muscle Man manages to do it perfectly and wins the competition.]]
613* ''Franchise/{{Transformers}}'' examples:
614** In ''WesternAnimation/TheTransformers'', Elita One turned out to have the power to [[spoiler:[[TimeMaster freeze time]]]], but as Alpha Trion had warned her, using it [[CastFromHitPoints drained]] her LifeEnergy to a near-fatal level.
615** Also in ''Franchise/TransformersGeneration1'', Megatron has the ability to draw anti-matter from black holes and pretty much blow up all of his surroundings. It was used about twice in the Marvel comics, where it was explained he didn't often use it because he was liable to kill himself too.
616** G1 again, Windcharger can create magnetic fields capable of ripping apart even the strongest of metal structures. It burns him up very rapidly though.
617** In ''Anime/TransformersCybertron,'' Vector Prime would [[spoiler:greatly tax himself reversing time by a few minutes, and eventually die by using his time/space powers to get the team through the rift separating Gigantion from the normal universe.]]
618* In WesternAnimation/BeastWars there's overriding your stasis lock, as shown in Dinobot's DyingMomentOfAwesome. Simply put, when a Transformer's energy reserves are 96% depleted their systems automatically undergo a stasis lock so that they won't exhaust themselves to death. By overriding it you can use that last 4% to buy yourself enough time for reinforcements to arrive, or in Dinobot's case, take out the entire Predacon team sent to kill the first protohumans and thwart Megatron's attempt to permanently wipe them out.
619* In ''WesternAnimation/{{WITCH}}'', the [[ElementalPowers Guardians]] can choose to transform into living embodiments of their elements, giving them PhysicalGod levels of power -- at the risk of losing their personalities and humanity, and being left open to mental domination from outside forces, such as BigBad Nerissa. [[spoiler:Fortunately, the one time they do this, they manage to come back - barely]].
620* ''WesternAnimation/YoungJustice:'' Using the Helmet of Fate is this, because Nabu, the Lord of Order, wants a permanent host rather than have his power be used temporarily. Kid Flash and Aqualad both avoid this fate thanks to the spirit of Kent Nelson, the previous wielder, convincing Nabu to let them go. [[spoiler:However, when Zatanna uses the helmet to stop Klarion, Nabu chooses her as his next wielder, and had already forced Kent Nelson's spirit to move on. The only reason she was released was that her father Zatara negotiated her freedom by offering himself as the next Doctor Fate]].
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623[[folder:Real Life]]
624* Backfired with the destruction of HMS ''Invincible'' at Jutland. The Dangerous Forbidden Technique, in this case, was the bypassing of safety protocols designed to prevent flashdown of a detonation in a turret from reaching the magazines, and it was done to increase the rate of fire. But ''Invincible'' was pounding the crap out of the German SMS ''Lutzow'', so why not? Why not, indeed. The mist that was hiding her cleared, just long enough for the critically damaged but afloat ''Lutzow''[[note]]At the end of the battle, ''Lutzow'' was too badly damaged to withdraw and was scuttled.[[/note]], along with a second German battlecruiser SMS ''Derfflinger'', to get some solid hits in the right place, and ''Invincible'' was blown in two. At least one and possibly both of the other British battlecruisers lost that day went up for the same reason. The fact that British ships of UsefulNotes/WorldWarI used more volatile gunpowder than their German counterparts didn't help, either.
625** Similarly, many tanks have manually- or power-operated doors separating the ammunition locker from the turret, to keep a strike that penetrates the locker, or an onboard fire, from cooking off shells and killing the crew. Sometimes these doors will be disabled or removed to increase the rate of fire, but it's obviously not an approved practice.
626* Another naval example would be the Japanese mounting the infamous "Long-Lance" torpedo on their cruisers. The torpedoes were stealthier than most, but also much more volatile. Thus, if they were hit while still on the ship the resulting explosion often crippled the ship. This happened to the cruiser ''Chokai'' during the Battle of Samar, which was fired on by the single 5" gun of the escort carrier USS ''White Plains''. While [[JokeWeapon usually incapable of penetrating a cruiser's armor]], one hit set off eight torpedoes, [[MadeOfExplodium each with a 1000-pound warhead and a tank full of pure oxygen propellant.]] The resulting explosion [[CherryTapping knocked out the engines]] and the ''Chokai'' had to be scuttled. This made the Chokai the only enemy ship ever destroyed by a carrier's deck guns.
627* The [[ExactlyWhatItSaysOnTheTin Mordhau]] [[note]]"murder-stroke" or "murder-strike"[[/note]] in [[UsefulNotes/EuropeanSwordsmanship German school of swordsmanship]]. BilingualBonus applies why it is forbidden in friendly combat where the aim is NOT to kill your opponent. True, it may seem odd how, in a fight with big, sharp implements it's [[ImprobableUseOfAWeapon smashing someone with the handle]][[note]]specifically, grasping the sword by the blade and using the pommel as a mace[[/note]] that's forbidden, but that thing is heavy and tends to ignore the fact the victim's wearing metal armor[[note]]like a mace, it can easily cause blunt injuries through armor[[/note]]. It has that name for a ''reason''.
628* In soccer, the awesome techniques of jumping up in the air and trying to hit a ball next to another player is usually forbidden, because it could hurt the other player if he'd get hit by a flying boot. A little more mild, but still similar is the "scissors" technique of scoring.
629* [[NukeEm Nuclear weapons]]. Nukes are capable of great destruction, but actually using one comes at a hefty price. Large nuclear detonations release irradiated material into the surrounding environment that remains dangerous long after the explosion is over. In a more immediate sense, several nations have active nuclear weapons that are kept ready for launch at all times. Since there is currently no viable way to defend against a nuclear weapon after it's been launched, the target has no reason not to fire all its weapons at the aggressor. This is the concept of Mutual Assured Destruction (MAD) and it effectively makes using nukes suicidal. Note that in World War II, this was not an issue; with no other nuclear-capable countries to provide the "Mutual" portion of MAD, the United States was free to attack Japan without fear of similar retribution.
630** Though [[UsefulNotes/PeaceThroughSuperiorFirepower eight]] [[UsefulNotes/FromRussiaWithNukes nations]] [[UsefulNotes/TheDragonsTeeth are]] [[UsefulNotes/UltimateDefenceOfTheRealm declared]] [[UsefulNotes/TheUltimateResistance to]] [[UsefulNotes/TheThirdEyeOfBharat have]] [[UsefulNotes/PakAttack nuclear]] [[UsefulNotes/TheHoovesOfChollima weapons]] (and [[UsefulNotes/TheSamsonOption one is suspected]]) most nuclear powers refuse to consider using nuclear weapons unless someone else does first. Nowadays, the worry is more about the dangers of non-state actors (ie. terrorists) using them instead, which [=MAD=] is essentially powerless against.
631** Even nukes aren't necessarily as repellent as biological warfare. At least a nuclear weapon only destroys its targeted area, however horribly; use of biological agents as weapons poses a ''very'' real risk of infecting everyone the contagion touches, be they enemy, ally, innocent bystanders, or one's own side.
632* This trope is usually defied in real life, due to [[CombatPragmatist Combat Pragmatism]] being a time-honored military and general combative doctrine. If it's dangerous and highly lethal, using it is the best way to win. If it's forbidden, all the better because that means the other guy will never see it coming.
633* There are international [[UsefulNotes/TheLawsAndCustomsOfWar Laws and Customs of War]], that ban war tactics such as [[ShootTheMedicFirst shooting the medic]] and [[RapePillageAndBurn deliberately harming civilians]]
634* Overdosing on caffeine as a deadline draws nearer.
635** Recreational drugs in general, actually. The more intense a drug's effects are, the more likely it is to cause harm if not moderated, along with the need for more strict moderation. And the more intense effects you experience, the more curious you'll get for even stronger experiences. Though just because an experience is weak doesn't mean the damage is light: air duster as an extreme example. Alcohol is an aversion, though: drinking more after getting buzzed actually decreases the euphoria and eventually can cause severe depression and rage.
636* There's a popular recipe among Russian students which consists of mixing 50 ml of Coke with 2 teaspoons of granulated coffee. Due to how it works on your body (Coke pretty much expands your blood vessels and makes caffeine go into the bloodstream much faster, multiplying its effect), it can give you a huge energy boost for 8 to 14 hours. On the other side, even a single cup can have some harmful effects on your health, from high blood pressure to body tremors, not to mention that it's a guaranteed way to ruin your sleep schedule.
637* Not exactly a technique, but human muscles are actually so strong that they can ''rip themselves off your bones''. Usually, the body has all kinds of limitations on itself to prevent it from happening, like pain. But in situations where super strength is the meaning of life or death (like being slowly crushed under some heavy boulder), [[UninhibitedMusclePower the body can drop these limits by itself]]. It'll save your life when needed but at a really really painful cost. It will eventually heal, ''if'' you're able to find a doctor who can properly set your broken bones and muscles so that the ligaments and tendons heal naturally. And, also, you'll need to follow his protocols for recovery ''to the letter''.
638* Steroids, blood doping, performance-enhancing drugs, and other methods are illegal in most official events, partly for this reason.
639* Water methanol injection, also called as War Emergency Power, on turbocharged internal combustion engines. Injecting 1:1 water-methanol mixture into the combustion chamber can boost the performance of the engine by up to 33% and add up extra horsepowers. It basically acts as a chemical intercooler. Unfortunately, its prolonged use (we speak about minutes here) will also damage the cylinder heads. In WWII, its use was approved only for emergency situations, like an airplane escaping from a [[AcePilot particularly nasty enemy]], and using the mechanism involved in breaking the seals. On Allied planes, this 'seal' was a thin wire stretched across the throttle assembly at the point where WEP would engage. The wire was strong enough to prevent a pilot from accidentally activating WEP, but could be broken fairly easily if the pilot deliberately pushed the throttle; the idea was, when the mechanics back at base inspected the plane after a mission, they would check this wire. If the wire was intact, the engine was okay, but if it was broken, then the mechanics knew the engine would have to be pulled out of the plane and rebuilt.
640** Likewise [[NitroBoost nitrous oxide injection]] called [[BilingualBonus ''Ha-Ha-Gerät'']] in the Luftwaffe, which acts as a chemical ''turbocharger''. It will boost the performance, but long periods of use will seriously damage the engine.
641** This is the effect of pushing the engine past its rated limits. What's on paper is what the manufacturer has safely determined the engine will go up to without dying sooner than how long it's expected to last. You could always push an engine harder, but doing so wears it out faster. Sometimes ''much'' faster, if the strain you put on the engine passes what its structural integrity can handle, causing it to tear itself apart or burst into flames.
642** In modern military aircraft, afterburners can certainly count in some cases. The way they work is by taking raw jet fuel from your tanks and spraying it directly into the VERY hot exhaust section of the engine. This, in turn, adds up to a sudden burst of power from the engine which will get your aircraft from just barely scratching the sound barrier to moving twice the speed of sound in the span of a minute or so depending on the aircraft. This comes at a price, however. Normally, afterburner use is relegated to take off, or on a bolter[[note]] When a naval aircraft misses all of the wires and needs the extra power to get back in the air[[/note]]. These short bursts normally don't do much damage to the engine, but using it too often (as in the case with most dogfights), can shorten the life span of your engine, meaning it'll have to be changed out once you return to base. However, use the afterburners too much, and you won't even have to worry about that, because your aircraft will eventually clunk into the ground with not even a drop of fuel left in the tanks.
643* 'Cooking off' grenades involves pulling the pin and allowing it to tick closer to detonation before throwing it to the target. Successfully pulling it off results in the grenade exploding mid-air, showering the enemy with shrapnel while giving them less time (if any) to pick it up and throw it somewhere else. Failure results in the grenade exploding in your hand, [[BoomInTheHand which is unpleasant]], to say the least. The fuse of a grenade is not so exact that you dare do this; there's enough wiggle room that you (and any member of TheSquad standing too close) can be reduced to PinkMist while you think you still have a little more time. And if you happen to get shot, lethally or not, with a cooked grenade in your hand...
644* Overclocking a PC's CPU can help squeeze in a performance boost, but this is not something to be done casually; without a good cooling system to offset the increased generation of heat, overclocking is a good way to ensure that you'll be shopping for a costly replacement CPU.
645* Believe it or not, there is one when playing {{pinball}}: The [[https://www.youtube.com/watch?v=KB8Xp4PMvbQ Bang Back]] technique involves giving a nice solid punch to the bottom of the machine. When done as the ball is traveling down the left outlane and into the drain, you can potentially save it and continue playing. Doing so, however, will probably hurt your fist and damage the machine with it. Even more so during the time manufacturers installed nails onto the bottom to impale the hands of players who attempted this. Nevertheless, the potential harm the Bang Back can do, as well as the technique allowing you to keep playing for far longer than is intended, means even attempting one is grounds for instant disqualification at all tournaments, big or small.
646* Bee's stings. They cause enough pain to their victim that they're either out of commission or deterred from attacking their hive. They also involve the bee's stinger embedding itself in the victim's flesh dragging the poison sac (and several vital organs) along with it, killing the insect. For this reason, bees only sting in response to a serious threat to their hive or queen.
647** However, this only applies to certain kinds of bees. While not wasteful of their stings, other bees CAN live after stinging. (It's also worth noting that this only occurs in (a subset of) those insects that are ''scientifically'' classified as bees; other types of stinging insects, though they are often referred to colloquially as "bees", are not true bees and do not have this limitation.)
648** This only applies to vertebrates, however. Bees can sting ''insects'' with impunity as their stingers have no problems with exoskeletons. They just get stuck in fleshier victims. Their (lack of) aggression has more complicated evolutionary origins and depends largely on the individual species.
649* Neutrophil white blood cells, considered the front line of the immune system, include in their arsenal besides phagocyting enemy microorganisms or releasing antimicrobial enzymes to launch [[https://en.wikipedia.org/wiki/Neutrophil_extracellular_traps webs of DNA]] to bind and kill pathogens. While effective against the latter, not only releasing them may [[SuicideAttack kill the neutrophil]], even if [[WeHaveReserves there's plenty of them]], but also cause damage to the host's tissues and organs as thought to happen in COVID-19 infections.
650* The act of redlining. Many machines, typically those with an engine of some sort are fully capable of operating at a capacity beyond what their components are designed to safely tolerate (for example, the rpm meter of your car likely has markings in red showing where this starts). You can get a boost in performance power by pushing past these safe limits in exchange for a significant increase of wear and tear on the machine’s parts and a high risk of the machine breaking.
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