->''"By opening all eight gates, you could attain power beyond even the Hokage. The only drawback is... you die."''
-->-- '''Kakashi''' on the Hidden Lotus technique, ''Manga/{{Naruto}}''

There are [[TheDarkArts some attacks]] in the media that come at a price. Actually, there are a ''lot'' of attacks in media that [[PowerAtAPrice come at a price.]]

Perhaps the technique conducts a horrible toll on the person's [[CastFromHitPoints body]]. Perhaps it's horribly [[BadPowersBadPeople immoral]] or [[WithGreatPowerComesGreatInsanity damaging to the mind]]. Perhaps it [[SummonBiggerFish calls up monsters that can't easily be controlled]].

Whatever the case, the character's mentor will tell him that he can only use said attack a set number of times or he's never supposed to use it unless some requirement is met. Expect the OldMaster to inform the hero that YouAreNotReady. And [[RuleOfDrama naturally]], a situation ''will'' come up where the character has no choice but to use the technique, or if it has a limited number of times it can be used safely, he or she will be forced to use it more than the safe number of times. Like ForbiddenChekhovsGun, this technique (or rather, its overuse) comes at a ''heavy'' price. Unlike ForbiddenChekhovsGun, the price is [[NecessaryDrawback nearly always paid]].

If the hero is ''lucky'', it could just be a HeroicRROD. But it's often worse than that. Sometimes it unleashes their SuperpoweredEvilSide.

Compare DeadlyUpgrade, CastFromHitPoints, CastFromLifespan, SacrificialRevivalSpell, DeathOrGloryAttack. If they constantly survive these it's a case of IThoughtItWasForbidden. See also GodzillaThreshold and LethalHarmlessPowers.


* ''Manga/{{Naruto}}'' has lots and lots and lots of these. In fact, there exists a specific subset of the Shinobi arts called 'Kinjutsu', literally "Forbidden Techniques". For one reason or another they have been banned from being taught, used, or both by the commanding shinobi. They are either jutsu that damage the user to a fatal extent (e.g. Mass Shadow Clone Technique: Each Shadowclone takes a portion of the shinobi's chakra for himself. Make too many Shadowclones, and the original will probably die from exhaustion), jutsu that are viewed as ethically wrong (such as Edo Tensei which resurrects the dead) or jutsu which involve other crimes (e.g. murder in case of the "Edo Tensei," because a HumanSacrifice is needed to resurrect someone). There also exists a wide range of techniques that are not officially 'kinjutsu' but fit this trope.
** Sasuke's Chidori is only supposed to be used twice, but he uses it a third time; the result is that his cursed seal activates and nearly takes over (the technique later loses its "Dangerous" element, as Sasuke is able to spam the crap out of it without becoming exhausted). Just about every move Rock Lee uses that isn't a basic punch or kick carries some heavy toll on his body (such as his use of the Chakra Gates), and as a result, Gai forces prerequisites upon him, so that he must be protecting someone or defending his ninja way when he uses said moves.
*** Sasuke gained the ability to use the Chidori more often by the growth of his chakra capacity. Kakashi has likewise increased the number of times he can use his own forbidden techniques, Raikiri (an enhanced Chidori) and Kamui (which [[OneHitKill sucks anything he looks at into another dimension]]). As Kakashi explained to Sasuke, when dealing with chakra-heavy jutsu it's essential for a ninja to know their limit. Attempting to exceed that limit will most likely cause the jutsu to fizzle, and the user will suffer potentially lethal chakra exhaustion. Thus, when Sasuke tried to use that third Chidori in a single day, if he didn't have the cursed seal it probably would've resulted in a SenselessSacrifice.
** In the second half of the manga, Naruto gains his Futon: Rasenshuriken, which is so powerful it actually causes widespread cellular damage in the arm he executes it with, which is far too minute for healing jutsus to repair. While Naruto's HealingFactor can still repair the damage on its own, having to heal from something that extensive still reduces his lifespan. Tsunade even tells him not to use it again. After mastering [[SuperMode Sage Mode]], he perfects it so he can throw it, thus nullifying the risk to himself.
** 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 a jutsu to truly breathe life into puppets, but stopped when the beta technique had a nasty side-effect of (you guessed it!) killing the user of the jutsu. [[spoiler:Chiyo winds up [[HeroicSacrifice using it]] to save Kazekage Gaara (yes, the same Gaara that houses a demon, not unlike the titular Naruto).]]
** Hell, the deeper level of his Kyuubi form actually shortens his lifespan too, as it involves repeatedly burning away and healing back Naruto's skin. That's without considering the whole SuperPoweredEvilSide transformation. [[spoiler:Eventually, Naruto befriends the Kyuubi, allowing him to access its full power without physically transforming and thus without any risks involved.]]
*** As does Tsunade's own regeneration jutsu, which is consequently only used when there's a danger of a much more drastic shortening of her lifespan.
** Pain has been shown to have [[spoiler:an ''[[WaveMotionGun incredibly]]'' powerful version of his gravity attack that takes off years of his life, but can ''destroy an entire city in one blast''. And he uses it.]]
*** However, Nagato is [[spoiler: an Uzumaki, which means he has his clan's longevity]], reducing the risk of Shinra Tensei's big version.
** The Dead Demon Sealing Technique summons the fricking Grim Reaper to [[YourSoulIsMine tear out your opponent's soul]], [[TakingYouWithMe and your own]], and then forces them to fight forever in its stomach.
** The recently revealed [[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 close forever]].
** Finally, there is Edo Tensei, a jutsu that sacrifices a living person to bring another back from the dead as a zombie with unlimited regenerative abilities. It is forbidden both because of being necromancy and because it is ridiculously broken - the undead not only regenerate from ashes as long as their soul is in place, allowing them to spam their own dangerous forbidden techniques with impunity, but since the chakra reserve is tied to physical stamina, the regeneration also keeps replenishing their energy. When it is used to its full potential by [[spoiler: Kabuto]], the resulting BossRush takes thousands of ninjas to stop.
*** The risk of Edo Tensei is [[spoiler: if an exceptionally powerful Edo Tensei, like Madara, knows the contract, they can break it. Thus even if the summoner cancels the technique, the Tensei would continue to exist...now free of the control.]]
** Quoted above is the Eight Inner Gates, a technique that grants exponentially greater amounts of strength each time one is opened, but with more and more strain on the user's body. If all eight are opened, the user becomes physically stronger than any human could otherwise manage. For a few minutes. [[DeadlyUpgrade Then you drop dead on the spot.]] Rock Lee, before the timeskip, was almost permanently crippled by using 5 gates and having his arm and leg crushed by Gaara. Might Guy, Lee's teacher, is stronger and more able to use it, but it's indicated that if he opens the eighth gate, death is guaranteed even for him.
*** A character is ultimately shown using all eight gates, and the resulting physical prowess not only surpasses that of all the characters known when the technique was first introduced, it surpasses that of even [[spoiler:[[PhysicalGod Madara Uchiha, who was hosting the Juubi to boot]]]]. After his final attack, his body is so overheated it starts dissolving into ash while he's still alive. [[spoiler: Naruto is able to prevent this, but Gai is shown to be in a wheelchair years later.]]
** Before any of these was what became Naruto's signature technique: the Tajū Kage Bunshin no Jutsu, or "Multiple Shadow Clone Technique." Multiple being somewhat of an understatement: the average ninja who was any good could make two or three shadow clones, a skilled chakra user with a strong reserve could make maybe a dozen simultaneously. The Tajū Kage Bunshin no Jutsu creates, on average, several ''hundred'' clones. It wasn't forbidden because of the power of the clones (they were still subject to the normal rules of shadow clones) but because a single usage was so draining it would instantly kill anyone who didn't have a superhuman chakra reserve, a Tailed Beast [[SealedEvilInACan sealed inside them]], or in Naruto's case, both.
* The title character from ''Manga/{{Inuyasha}}'' can allow his demonic blood to temporarily dominate him by casting aside his mystical {{BFS}}, or having it stolen, which means it borders between this trope and SuperpoweredEvilSide. This "demon form" makes him a lot stronger but the more times he uses it, the more [[DeadlyUpgrade his soul decays]]. This may not sound like much, but what it actually means is that he becomes a [[UnstoppableRage berserk, vicious killer]], and the more time he spends in this form, the more indiscriminate he becomes in choice of targets. It also becomes easier and easier to activate, and harder and harder to turn off... which means that he will, ultimately, become nothing but a mindless killing machine that can do nothing but wander aimlessly and slaughter everything in sight.
* ''Manga/RurouniKenshin'' used this trope on both Shishio and Kenshin. [[spoiler: The full body-bandaged Shishio would and did die from heat exhaustion after 15 minutes. Kenshin was forced to retire from swordmanship for good because of his overuse of the Hiten Mitsurugi Ryuu, as his fighting style is meant for more muscular men.]]
** Hiten Mitsurugi Ryuu also has an ultimate technique that involves putting yourself in significant danger. If you hesitate even the slightest amount, you either die or lose your leg. If you don't hesitate, you might still lose your leg.
** 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 damage.
* In ''Anime/DragonBallZ'', Goku was taught the Kaio-Ken by King Kai, but was told not to use it at more than double capacity. When he fought Vegeta, he had to use it at triple capacity, which hurt like hell, and then ''quadruple'' during the BeamOWar - after that, Yajirobe just patting him on the back made him scream in agony. By the time he fought Frieza, he could use the lower levels without any strain (King Kai had to tell the others that he'd been using it the whole time and wasn't holding back). He eventually used it ''multiplied by twenty'' -- the maximum, and still nowhere near enough to win. ''That'' wiped out his reserves and left him nearly defenseless.
** He was also warned about the power of the Spirit Bomb before returning to Earth, since the technique can destroy planets if misused.
** Another character, Tien, also had a forbidden technique: his Kikoho (Tri-Beam in the dub) will kill him if he uses it too much. Even when it doesn't kill him, it still exhausts him to the point of not being able to fight.
** There's also the Mafuba (Evil Containment Wave in the dub), the technique that Master Mutaito used to seal King Piccolo. The attack requires so much energy that it kills the user, as Master Mutaito died from using, and later on in the series, Master Roshi dies after unsuccessfully using it against the now-released King Piccolo.
** Vegeta's "Ultimate Final Skill" (suicide explosion, in games it's called Final Explosion, which reduces you to a single pixel of life). Of course, [[SenselessSacrifice it doesn't work on Buu]].
* In ''{{Eyeshield 21}}'', Hiruma orders Sena to seal the "Devil Bat Ghost" technique. At first he believes this is to stop competition from seeing it, unless it is coming at them. But when he later breaks these orders, he discovers that because he is yet to master the technique fully, it puts tremendous strain on his knees, and repeated use could injure him.
** The Devil Bat Dive is a lesser-used example, and for good reason. Using their try-for-point for a consecutive touchdown, the Devil Bat Dive requires him leaping over both lines, spinning, and falling into the end zone. Such a maneuver is dangerous in both fiction AND real life, which is why most teams just go for the kick less one of their players gets thrown into the ground head first.
* ''Manga/OnePiece'':
** In general, ''any'' ability gained by Devil Fruit may be considered this. Some abilities can give the user amazing powers (some are more useful than others) but it always comes with a potentially lethal side-effect, especially considering that this is an OceanPunk series: the user permanently loses the ability to swim. Pirates who take a chance and use the stuff are truly risking their lives, especially those who brave the dangers of the Grand Line.
** Hero Water (Fatal Elixer) in the Alabasta arc. Drinking it massively magnifies all of your physical attributes for five minutes. Then you die.
** During the Skypiea arc, a device is introduced called the Impact Dial, which absorbs any force that strikes it and then deals it back when the button is pressed, though it seems to cause a great deal of pain to the user's arm. Also introduced is its extremely rare counterpart: the Reject Dial, which deals back the force absorbed multiplied by ten. Using that has a large chance of destroying the user as well as his or her opponent. Wiper, a character intent on killing the BigBad of that arc with the Reject Dial, uses the item ''thrice'' (once against one of his CoDragons, once against the Big Bad himself, and once against the beanstalk Giant Jack in order to give Luffy the advantage he needed to get to the Big Bad), and though his body does take massive damage, he escapes alive.
** Luffy's SuperMode techniques, the Gears, are this as well.
*** First is Gear Second, though it mostly applies only Pre-TimeSkip. He uses his legs as a pump to accelerate the blood flow around his body, upgrading his strength and speed dramatically; for a normal human, that much acceleration would make their heart burst, but [[RubberMan Luffy's rubber organs]] can withstand it. When he uses it against Rob Lucci, the DragonInChief not only deduces how the form works, but informs him that it's doing more than severely cutting his stamina, it's actually cutting into his life-force and could shorten his life span! Of course, this doesn't prevent Luffy from using the move ''[[{{Determinator}} twice]]'' in the same fight, and further more times against [[LetsGetDangerous strong opponents. More so in the anime.]]
*** Next is Gear Third, which only applies pre-Time Skip. He blows air into his bones, enlarging his body parts, and consequently his strength, to giant sizes. The downside was that it only worked for long enough to launch a couple of attacks; after that, as the air left Luffy, he was reduced to a Chibi form for a few minutes, leaving him very vulnerable. But post-Time Skip, he's overcome that weakness.
*** But his post-Time Skip technique, Gear Fourth, definitely falls under this trope. [[spoiler:He inflates his muscles rather than his bones and augments his whole body with Armament Haki. His strength skyrockets—Gear Second and Third can't even compare to it—and he can even use the ability to fly. The downside is that it has a time limit, and as soon as that time runs out, Luffy is left in an exhausted mess, unable to use Haki for ten minutes.]] It's a massive trump card…but very dangerous.
** Also pre-Time Skip is Chopper's Monster Point form. By using the Rumble Ball, he can expand his MultiformBalance to have seven forms rather than the standard three afforded to all Zoans. The downside is that the Rumble Ball's effects only last for three minutes, and he can only have one every six hours. If he takes two, he loses control of his transformations, and if he takes three…that's when Monster Point is unleashed. The power of it is incredible, allowing him to instantaneously change which end of a CurbStompBattle he's on, but it's a berserker form, so allies are in as much danger as enemies. The form also requires a colossal amount of energy to maintain; staying in it for too long would kill Chopper, and when he changes back to normal, it takes a long time before he can manage to move anything other than his eyes and mouth.
*** Post-Time Skip, Monster Point is still this, but to a much lesser degree; through research and training, Chopper is now able to enter Monster Point by eating a Rumble Ball and maintain control of the form for three minutes. But it still takes a massive amount of energy; as soon as he turns back, his body is rendered immobile from exhaustion for the next few hours.
** Rob Lucci has one of these as well. The Rokuogan (Six King Gun/Pistol) strikes his opponent with a shock wave comparable to a Reject Dial, but using it expends a ridiculous amount of energy. In fact, using this technique was what led to him losing enough stamina for Luffy to defeat him…albeit barely.
** The Energy Steroids from the Fishman Island arc. They give extremely great power, endurance, and stamina, but every one consumed shortens the consumer's lifespan…and quite possibly their sanity as well.
* ''Manga/{{Bleach}}'':
** 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, and only after he learned the truth about his birth was he able to face the full truth of his power and accept his hollow as his true asauchi.]]
** In his battle with [[MadScientist Mayuri]], Uryuu activated [[OneWingedAngel Letzt Stil]], considered the last resort of the Quincy. His [[OldMaster grandfather]] had taught Uryuu 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 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 Final Arc, we learn that there is a way to obtain Letzt Stil powers without the one-time-only drawback...but it is forbidden to traditionalists like the Ishidas as unethical.]]
** Certain [[FunctionalMagic Kidou]] is classified as forbidden. Tessai was exiled with Urahara for using forbidden kidou that manipulated space-time. Yamamoto also used a forbidden sacrificial kidou; he sacrificed his left arm to create a massive pillar of fire in an attempt to kill Aizen.
** Captain Komamura's clan has the Human Transformation Technique, which turns them from anthropomorphic wolves into full humans with a power boost. [[spoiler: It requires giving up your human heart, and when the technique runs out, leaves the user as a full non-anthropomorphic wolf]].
* Towards the end of the Chimera Ant arc of ''HunterXHunter'', [[spoiler: Gon forced himself to grow by shortening his lifespan, using all his inborn talent to reach the power that rivals the King of Ants (strongest character as of now), with the possibility of never being able to use nen ever again (and having lifespan shortened)]]
* ''Anime/YuGiOh'': Industrial Illusions has the [[IdiotBall decidedly odd practice]] of designing cards "too powerful and dangerous to be used," requiring they 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.)
** In ''Anime/YuGiOhGX'', there's also something called the "Cyber Legacy", which Kaiser Ryō is the inheritor to. 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 (Cyber Dragon and other Cyber-type monsters), 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]].]]
** In the real game cards deemed too powerful are forbidden from official tournaments. If only they could be consistent on what overpowered means.
* Ryoga Hibiki's "Shishi Hōkōdan" in ''Manga/RanmaOneHalf''. This [[KiAttacks Ki Attack]] is fueled by the user's depression and melancholy. So to acquire more power the user will purposely do things to become more depressed. When Cologne sees Ranma and Ryoga trying to out-depress each other while blasting the technique freely, she compares them to a pair of lions fighting as they roll off a precipice and to their deaths.
** The Shishi Hōkōdan is actually an interesting example on two accounts. First, Ranma tries and fails to beat Ryoga at his own game, and realizes the flaw in the principle-namely, as the tide of battle turns, the loser will gain great power for the technique by his depression at losing the fight while the winner's lightened spirits will depower the technique. So he creates his own, Not-So-Dangerous, Not-Actually-Forbidden Technique in the form of a KiAttack fueled by boundless confidence. Second, Ryoga is baffled when the scroll he learns the technique from indicates a general sense of downwardness; it turns out that in it's purest form Shishi Hōkōdan isn't a directed beam, it's more like a weight dropping on the user from the heavens; the user is protected from his own attack because he's emotionally empty when he uses it. Ranma uses this against Ryoga by jolting him out of his reverie mid-attack with [[PantyShot something he knows Ryoga wants from Akane]]; the surging hope and anticipation leave Ryoga open to being clobbered by his own technique.
** Surprisingly, Genma himself developed his own DangerousForbiddenTechnique: the [[CombatPragmatist Yamasenken]] and [[StealthRun Umisenken]], seriously and unusually (for this series) lethal techniques which equate the structure of a body with that of a house. Though initially developed [[spoiler: as tools for burglary and thievery]], the techniques comprised by these two schools are designed for fun things such as ripping out an opponent's heart, tearing an opponent's throat, strangulation, and cutting up enemies into itty bitty pieces using nothing but air pressure. Genma was loath to teach Ranma anything about them, on the grounds that they were far too dangerous, and only acquiesced when he learned Ryu Kumon was using the Yamasenken. Even then, when Ranma and Ryu dueled using these two opposite schools, Ranma did so with the stipulation that, if he won, Ryu would seal the techniques forever.
** 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... and then it turns out to be nothing more than a fancy name for throwing homemade firecracker bombs around. [[ImprobableWeaponUser They are actually quite effective weapons, though.]]
* ''OutlawStar'' featured the Caster gun which fired spiritual Caster Bullets (each type represented by a number, but the differences were never fully established for most of them.) Eventually, Gene realizes that there are three numbers that never come up, so he tracks down the gunsmiths that make these bullets. Each one gives him one of these bullets (except for the #4 bullet, which he receives 2 of), but explain that they draw on the gunner's soul, so if he fires all three, he will die. Sure enough, he needs all three.
** A slight inversion in the fact that these shells weren't originally designed to be harmful. It's just that there's so little mana left in the universe, that [[CastFromHitPoints taking away lifeforce]] is the only thing powerful enough left. And when he did fire his last shell, he did drop dead; so did his enemy. He was saved because the place he was in ([[spoiler:the Galactic Leyline]]) noticed ''everyone'' inside was dead and performed an AutoRevive.
* Almost everybody in ''GetBackers'': Ginji starts going crazy if 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.
* 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.
* ''MahouSenseiNegima'''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. [[spoiler:In Chapter 249, we see the first sign of the possible consequence of using Magia Erebia.]]
** And [[spoiler: chapter 265, we see [[UnstoppableRage just why]] this could become a problem]].
** And the ''real'' direct consequence of Dark Magic finally shows up with [[spoiler:Negi basically overdosing on magic and poisoning himself, which is now requiring him to have to battle inside himself to get an upper hand on the dark magic. Eva isn't even sure this is ''possible'' because as she noted earlier, Negi has already surpassed her in his mastery of this technique. Oh, and even if he wins he apparently won't be exactly human anymore.]]
** And even then, it's only a temporary fix.
* In ''TheSlayers'', Lina's Giga Slave is the mother of all [[DangerousForbiddenTechnique Dangerous Forbidden Techniques]]: It consists of [[spoiler:summoning a fragment of [[{{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 counts, since it consumes magic quickly enough to put the caster's life in danger if they try to maintain it for too long.
* Suffering from DatingSim withdrawal, Keima of ''Manga/TheWorldGodOnlyKnows'' 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, and eventually passes out under the strain.
*** One hour after the mode is activated, its user will have lost three years of his life! (Or at least he'll be so tired it feels that way!)
** He then takes it even further by playing "24" games at once.
* It's revealed in the third season of ''MagicalGirlLyricalNanoha'' 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, led to her being critically injured and hospitalized for nearly a year.
** Actually, it was Nanoha's training regimen that resulted in her being low on energy during a battle, and the wounds she got very nearly killed her. However, the DeadlyUpgrade that is the Blaster System defintely qualifies for this trope: if Nanoha's body is likened to a massive wooden building with fireplaces which supply magic to her, the Blaster System doesn't add fuel to the fire so much as it ''sets part of the building ablaze.'' In the following supplements, it's revealed that [[spoiler: her use of the Blaster System during the JS incident permanently decreased her magical potential by about eight percent.]]
*** It is, however, revealed that the [[WaveMotionGun Starlight Breaker]] compresses magic in such a way that when used the way Nanoha does it, compared to the way Reinforce [[SphereOfDestruction used it]], actually does put tremendous strain on her body, when combined with her training regimen, is what caused her to get critically injured.
* Jin from ''SamuraiChamploo'' learns his master's DangerousForbiddenTechnique 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 (his sword is stuck in Jin) to strike him down.]]
* ''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 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]]. The armour is still useful, but has to be ejected on the battlefield right after each use to avoid melting the Liger Zero.
* In ''SoulEater'', 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.]]
* Two notable examples exist in ''Franchise/SailorMoon'': Sailor Pluto, who will die if she uses the power to stop time, and Sailor Saturn, who will die if she uses her power of destruction.
** They [[spoiler:both break the taboo in the [[Manga/SailorMoon manga]] anyway and actually do die -- in Pluto's case for a whole arc -- before coming back fairly nonchalant and well-adjusted about the whole thing.]]
** In the [[Anime/SailorMoon anime]] there's also the whole Silver Crystal bit - use it at full power, which equates to a KamehameHadoken 9 times out of 10, and the user is killed. They get one last wish, though and it's usually enough to reverse it. This is not true of the manga.
* In 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 enough, the dragon can turn on the caster and devour him. [[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.]]
** The first time he used it, he also had to offer the use of his right arm as a sacrifice.
* Train from ''Manga/BlackCat'' can only use railguns 5 times per day. In the final battle, he squeezed out 6th shot, resulting in him unable to perform it anymore. He's not worried, though, since he has already taken care of the BigBad.
** And Sven's eye ability makes him very tired after using it, which limits him as well, though his ability isn't near as badass.
* Parodied in NininGaShinobuden, where the technique that has been "banned ten years ago because it was so dangerous" is...duct tape underpants.
* In ''CodeBreaker'', Toki Fujiwara's usage of his Gauss Cannon will damage whatever arm that he uses to fire. Thus meaning he can't fire more than twice overall in a fight. Every code breakers are in danger of suffering "after effects" when they overexceed usage of their powers.
* The Experts in ''GiantRobo'' apparently have this. For some, using their powers to an extraordinary extent is this -- we get to see a mook burn himself to near-ashes with his pyrokinesis, trying to keep his buddies warm. For others, using their powers in excessive ways is this -- [[spoiler:Alberto the Shockwave breaks apart after absorbing the Monster Sphere's energy field, for example]]. And for at least one, using his power ''at all'' is this.
* 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 a 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]].
* In ''SaintSeiya'', Dragon Saint Shiryu was 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 has a last-minute change of heart and manages to send him back to Earth with just a 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 against an opponent that had beat everyone else, but stopped when doing so would destroy a MacGuffin that was needed.
** Athena Exclamation, 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]].
* In ''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.
* ''Manga/ThePrinceOfTennis'':
** The technique "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]].
** There are quite a few others as well: Tezuka Phantom and Zero Shiki Serve, Ryoma's Cyclone Smash, Atobe's Tannhauser Serve, Sanada's Rai...
* The NT-D ("Newtype Destroyer") system in ''GundamUnicorn''. 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.
* In ''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.
* In ''{{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.
* You wouldn't expect this from an anime about the ''circus,'' but the arcplot of ''Anime/KaleidoStar'' revolved around one of these. There was a DangerousForbiddenTechnique for trapeze and highwire artists that 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 DangerousForbiddenTechnique was what killed [[spoiler: Karlos']] old partner, becoming [[MyGreatestFailure His Greatest Failure]] and turning him into TheAtoner.
** Needless to say, by the end of the series, [[spoiler: Sora and Layla]] perform it successfully. Doing it even once is enough to [[spoiler: cripple Layla for life and end her circus career forever.]]
* {{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.
* Being a Deconstruction of the FightingSeries PlayedForLaughs, MutekiKanbanMusume parodies this trope when Kankuro tries to decide what thing he would imitate to beat Miki.
--> '''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]]?''
-->'''Akihiko:''' ''Shouldn’t you have already decided on that?''
-->Flashback of Miki being {{Curb Stomp Battle}}d by her mother, a fat restaurant hostess.
-->'''Kankuro:''' ''That’s impossible, [[VerbalTic nya]].''
* In ''Anime/DennouCoil'', 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]].]]
* ''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.
* In ''LightNovel/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.

[[folder: Comic Books ]]
* In the Marvel universe, there exists a weapon called the Ultimate Nullifier which can RetGone anyone or anything the user chooses. '''''But''''' if the target isn't visualized perfectly by the user, then ''the user'' is the one who gets erased. This is possibly the only weapon that can truly defeat {{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.)
* The "Demon Ball" technique in ''BowlingKing''; Its creator injured himself badly attempting to perfect it and was forced to retire from professional bowling.
* 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.
* ''ComicBook/TheMightyThor'' supporting character 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]].
* 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.


[[folder: FanWorks ]]
* FanFic/AGrowingAffection has a few:
** 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.]]
** 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.
* Twilight mentions in ''Fanfic/GettingBackOnYourHooves'' 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.]]
* In ''Fanfic/{{Pokeumans}}'', [[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.
** 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.
* Parodied in a ''Fanfic/JusticeSocietyOfJapan'' omake, where [[DragonBallZ Mr. Satan]] and [[StreetFighter Dan Hibiki]] both claim to know one of these, but are both to scared to actually perform it.
* ''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've drunken, of which Myst needed to drink a whole buckets worth in order 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 [[spoiler: killing her]] if she were to release that much power at once. As such, she has never once used it so far.
* In ''[[FanFic/SovereignGFCOrigins Origins]]'', a ''MassEffect''[=/=]''StarWars''[[spoiler:[=/=]''[=Borderlands=]''[=/=]''[=Halo=]'']] MassiveMultiplayerCrossover, Dr. Kevin Filner comes up with something that's considered this. 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.
* Subverted in the ''{{Manga/Naruto}}'' story ''{{FanFic/Vapors}}'', 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.

* The entire point of TheDarkSide in ''Franchise/StarWars''.
** Per [[AllThereInTheManual The Expanded Universe]], the [[ImplausibleFencingPowers lightsaber]] form [[AxCrazy Juyo/Vaapad]], which is the most powerful of them all but [[PowerAtAPrice relies on the heavy use of aggression]]. For that reason, it's forbidden to most Jedi except those who demonstrate they're capable of handling it safely (eg. [[BadAss Mace Windu]] and [[{{Badass}} Depa Bilaba]] Mace's own apprentice who was even ''better'' at Vaapad than he was). Which is to say, handling it without slipping to the Dark Side. According to Palpatine's ExpandedUniverse commentary, this should come as no surprise because Juyo is actually a Sith fighting style.
* In ''Film/KissOfTheDragon'', JetLi describes the titular technique as "very secret, very forbidden". (Though that technique actually poses no danger to the user. It is forbidden because of its effect on the target.)
* In ''Film/BladesOfGlory'', the Iron Lotus is a 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 the woman's head cut off 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.
* 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.
* Shows up early in ''TheFastAndTheFurious'': 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.
* ''Film/{{Ghostbusters}}'': "Don't cross the streams!"

* Death magic in LoisMcMasterBujold's ''Literature/{{Chalion}}'' series 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. Not to mention that unsuccessful attempts/research are regarded as attempted murder at best and dealt with by temporal authorities as such.
** Of course, ''successful'' attempts at death magic are considered divine intervention, and not prosecutable under criminal law. This is a bit of a semantic point, since if successful there's usually nobody left to prosecute. Usually.
* The use of "balefire" in Robert Jordan's ''Literature/TheWheelOfTime'' is forbidden by the magic users of the world, and when people use it anyway, they're exceedingly careful with it - because balefire doesn't just obliterate its target, it [[RetGone goes back in time]] to do so, with all the potential paradox 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 minute uses it is seen as a sign of his rapidly deteriorating mental state impacting his judgement, though he is technically correct that balefire is the only way to ensure enemies such as the Forsaken are not ressurected by the Dark One.
** It wasn't just the cities disappearing that almost broke reality, but also having them reappear again as the destroyers were killed with balefire, and then having them vanish ''again'' if the person who did that ''also'' got killed with balefire. (Though Robert Jordan waffled on this a bit, at one point saying that the effects of balefire couldn't be undone by more balefire.)
** Picking apart a weave of the One Power rather than leaving it to dissipate is a DangerousForbiddenTechnique 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. [[spoiler:When Elayne tries and fails, it produces a burst of wind. A burst of wind with the force of a small nuclear explosion.]]
*** And a lasting "fallout" effect that makes it difficult to cast spells in the entire region for a year or more.
* Creator/MercedesLackey's ''[[Literature/HeraldsOfValdemar Last Herald Mage]]'' trilogy mentions 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 trilogy.
** It's also mentioned many other times in her other Valdemar works, and used at least once more on a very powerful scale. Where [[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]], 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]]. In its own way, it's just as much a DyingMomentOfAwesome.
* Literature/HarryPotter has spells that count as Dangerous Forbidden Techniques, such as the Unforgivable Curses and Fiendfyre.
** Ironically, despite the fact that there was supposedly no known countercurse or any means of defending yourself from Avada Kedavra, Harry Potter survived it ''three times'' in his life, two of which were direct hits. Voldemort survived it once as well (for the same reason Harry did the third time, so someone was clearly misinformed).
** The use of Horcruxes is so forbidden that it's nearly impossible to find any information on how to use it. Probably not least because it involves fracturing the soul, and doing ''that'' involves murdering people.
** Similarly, the drinking of unicorns' 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.
* Literature/ThePendragonAdventure: It turns out that [[spoiler: all Travelers can pretty much 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.]]
* In Anthony Reynolds's ''TabletopGame/{{Warhammer 40000}}'' novel ''[[Literature/WordBearers Dark Apostle]]'', creative thinking is viewed like this by the Mechanicus. Dangerous enough to be sealed away in a separate brain.
* The ''{{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 and/or for 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.
* In ''Literature/TheMagiciansNephew'', the {{Prequel}} to Literature/TheLionTheWitchAndTheWardrobe, there is a dark spell 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]] actually 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,]] [[SomeAnvilsNeedToBeDropped it's quite blatant]] [[AtomicHate what it's supposed to symbolize.]]
* ''Literature/TheDresdenFiles'':
** A wizard's death curse. Put simply, the wizard, usually when knowing s/he is about to die, draws up all the power stored in their body and mind and unleashes it in an extremely powerful spell, usually a curse on whoever was killing them. Of course, this leaves no energy to keep the brain or heart working, so the wizard dies immediately on casting.
** Hellfire, which is demonic power that enhances spells but only available when your soul is corrupted by a Fallen Angel. Soulfire, Hellfire's divine counterpart, actually uses the stuff that composes your ''soul'' as the power source. Use too much Soulfire, and your soul literally evaporates into your spells, killing you (and maybe then some).
* 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.
* In ''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.
* 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]].
* 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: castrate themselves]] and slowly makes the practitioner more and more feminized.
* 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 who the rest of the world is at war with.
* 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 then, DangerousForbiddenTechnique he's about to have a nervous breakdown because of the prolonged usage.

[[folder: Live Action TV ]]
* ''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...
* ''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.
* Used ''on'' the main character in 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]].
* 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.
* 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.
* ''Series/KamenRiderDouble'''s Twin Maximum, in which he activates two [[FinishingMove Maximum Drives]] at the same time, temporarily taking his power up to 200%. However, this puts an incredible strain on his body, [[spoiler:as demonstrated when Shotaro impulsively uses it in one battle, which lights him on fire and severely injures him. In the final battle of the series, Double's SuperMode is powerful enough that he can combine the Xtreme and Prism Memories' Maximum Drives without ill effect.]]
* 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 rebuilt the jump gate. On this occasions the planet was already deserted, and the heroes had to additional motive of rendering it inaccessible to grave robbers.
* Resurrection spells in ''Series/BuffyTheVampireSlayer''. They either turn the dead person into a zombie, or make them come back wrong and all screwed up.
** The heart removal technique for vampires was in the ''Series/{{Angel}}'' half. Most vamps won't go near it because they don't know how long they'll be invincible for, only that it could be minutes, hours or days, and then they die.
** 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.
* In ''Series/GameOfThrones'':
** 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.
** [[spoiler: Khal Drogo]] convinced by Daenerys, let's Mirri Maz Duur [[spoiler: cast a dangerous spell to keep him alive]]. It [[GoneHorriblyRight goes horribly right]].
* In ''{{Series/Merlin}}'', 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.
* 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.)
* The ''Series/StarTrekTheNextGeneration'' episode "The First Duty" involves a maneuver called the Koolvord Starburst, which is forbidden because the last time it was attempted a century earlier, all five cadets were killed. [[spoiler: Turns out it was attempted again, and another cadet paid the price.]]
* The curse that trapped the fairy tales character into our worlds, made them forget about their former life and in Series/OnceUponATime. Even the witches like Maleficent think casting the spell is crossing the line because you have to kill the one you love the most which leaves an emptiness inside you. Regina however did it to get her revenge on Snow White.

[[folder:Multiple Media]]
* Nova blasts from ''Franchise/{{Bionicle}}'', during which Toa characters 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 not-so-close vicinity.
* In the ''Franchise/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.

[[folder: Professional Wrestling]]
* 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 Kane switched finishers to the chokeslam and why the Undertaker developed the Last Ride.
** Speaking of the piledriver, an actual piledriver (not the tombstone version that the Brothers of Destruction use) is something that WWE superstars haven't been allowed to use for over a decade due to Owen Hart using the move on Steve Austin, giving him the neck injury that would eventually end his career (no offense to Owen). Come 2013, the fact that Punk used it at all, let alone on Cena (who's had a history of neck problems), upped the HolyShitQuotient of the match they were in. Said match is now considered one of the best TV matches in RAW history.
** Hulk Hogan with the Legdrop and Stone Cold Steve Austin 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.) But perhaps we should just cut this off right here and now and say that wrestling in general will pretty much fuck you up over time.
* Most aerial techniques, but the 450 Splash and the Shooting Star Press are really bad, not only do they wear your body down overtime, but messing up could seriously hurt you on the spot. Just ask BrockLesnar.
** Booker T'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.
* The diving headbutt, and German Suplex (which puts a lot of pressure on the spine), especially nasty since they were both moves that ChrisBenoit used...a lot.
* Technical wrestlers generally avoid this as most submissions don't actually put that much pressure on the body.
* Certain moves can get banned as part of a wrestling angle, usually by a heel authority figure.
** At the 2007 Survior Series, ShawnMichaels and 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.]]
** In 2008, VickieGuerrero banned TheUndertaker's then-recently-added submission move the 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 Teddy Long.
** In 2011, Vickie would strike once again, this time banning Edge's spear briefly, and firing him for using it. One week later, Teddy Long once again lifted the ban and reinstated Edge.
** In 2012, after Sheamus accidentally hit Ricardo Rodriguez with a brogue kick instead of intended target AlbertoDelRio, Del Rio and David Otunga tried to push general manager BookerT 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.

* The ''barra vasca'' style of javelin throwing. Originally stemming from a Basque martial art, it is basically throwing the javelin as if it was discus. The ''barra vasca'' is an immensely effective style, and a new world record was immediately made. The Finnish javelineers got enthused of this style, and pushed it UpToEleven by soaking their throwing hands in soap 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 at the advent of the Melbourne Olympics in 1956.

[[folder: Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons'':
** 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, centred on the caster. Given that the SquishyWizard is the norm in D, anyone attempting this strategy had better hope that the 50% chance of getting sent to another dimension comes up.
** 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.
** This is the point of the corrupt spells in the ''Book of Vile Darkness'' (and their ''Exalted Deeds'' counterparts, sacrifice 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)]].
** 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; it's 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...
** 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 camaign 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 succeeding 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.)
* 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.
* Several of the noble families from the ''TabletopGame/{{Ravenloft}}'' supplement ''Legacy of the Blood'' possess the knowledge of a DangerousForbiddenTechnique or two, usually in the form of feats that only family members or their elite henchmen can select.
* 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]].
* 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.
* ''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]].
* ''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).
** 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.
* 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.
** 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.
* 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.
* ''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.
* ''TabletopGame/MagicTheGathering'':
** 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.
** Most Demon Cards and Mechanics play on this in another way; they handicap you in some way or form (such as Echo Costs or requiring you to sacrifice a creature every turn) to maintain their power. The entire concept of Black Suicide builds on this, using cards that have disproportionate amount of power but delayed detrimental effects to win before said detrimental effects does them in. It's referred to as "tearing your arm off and beating your opponent's to death before you bleed out".
* ''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.
* 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 and 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.
** At least there are ways to turn that one to your advantage, like Prime Material Dragon. And 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.)
* 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).
* ''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.

[[folder: Video Games ]]
* In ''Franchise/KingdomHearts'', 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.]]
** In addition, many of the ''Kingdom Hearts'' villains themselves cannot control the darkness. 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 ''is'' GenreSavvy enough to follow 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.]]
* In the PhantasyStar series, Megid invokes this trope by name. In [[PhantasyStarII PS2]], it's CastFromHitPoints at a painful rate. In [[PhantasyStarIII PS3]] 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 ambience of the rest of the series, so any spell capable of leveling a city is pretty much the equivalent of the Tsar Bomba. In [[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.
* The Chaos Dunk from 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]]
* ''SonicTheHedgehog'': Similar to his [[SonicX anime counterpart]], Shadow the Hedgehog can gain an extreme power boost whenever he removes the bracelets from his arms. Unlike the 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.
** 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. [[SOnicAdventure2 Shadow]] [[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([[Sonic3AndKnuckles In Tails' case, the Super Emeralds and in Mecha's case, the Master Emerald]]) to even transform in the first place.
* In ''VideoGame/FinalFantasyIV'', 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.
** 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.
* 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.
* ''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 [[SuikodenI Suikoden]] game, which...[[ExactlyWhatItSaysOnTheTin eats souls]].
* In the ''MegaManBattleNetwork'' 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.
** 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.
* In ''VideoGame/TheWorldEndsWithYou'', 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.]]
** [[spoiler:Hanekoma]] later proceeds to [[spoiler:revive Minamimoto as a Taboo Noise]] He reveals this himself to the player in the [[spoiler:[[UnreliableNarrator secret reports]]]]
* Some Techniques and Spells in RomancingSaGa drain LifeEnergy if one is low leveled in That field of magic or if the weapon uses LifeEnergy for it's techniques.
* ''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...
** Exactly how forbidden to make it is left up to the player, though, and [[MultipleEndings affects the outcome of the plot.]]
* ''VideoGame/CastlevaniaOrderOfEcclesia'' has the Dominus glyphs; Dominus Anger and Dominus Hatred are direct attack glyphs with each use inflicting shitloads of damage at cost to your HP, while Dominus Agony amps all your stats immensely with gradual HP loss thrown in on top of that. Unless you use a healing item at some point, prolonged uses of these glyphs by themselves will kill you. The Dominus glyph union 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]].]]
** Earlier in the series, ''Portrait of Ruin'' subverts the hell out of this. Pretty much for the entire first half of the game, you get warned about how having Jonathan or any other non-Belmont use the true power of the Vampire Killer will drain their life force and eventually kill them if they overuse it. But when you do actually unlock its power in game, [[DoubleEntendre you can whip it all day long with absolutely no consequences whatsoever.]] Of course, it's possible that [[DoubleSubversion while Jonathan's fine now, he'll suffer its ill effects later down in life]].
* ''BreathOfFire: Dragon Quarter'' 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.
* ''VagrantStory'' has learned techniques that, when used, [[CastFromHitPoints drain a portion of your health]].
* Akuma's (Gouki in the original Japanese) fighting-style from ''StreetFighter'' has the Shun Goku Satsu attack. Until it was mastered by Akuma, it was generally assumed that using it would always be lethal to both. Of course, in-game, it's just a move that does a lot of damage...
* ''VideoGame/TeamFortress2'': There is an unlockable weapon for the Demoman class called The Eyelander, a massive sword which decapitates and heals its user on a killing blow. The downside is that having the sword in your loadout reduces your max HP by 25, because the blade ''feeds on your soul''.
** Averted when, upon killing enough people with the eyelander, the Demoman becomes second in max health only to the Heavy and in speed to the Scout (or a Soldier with the Equalizer at maximum effect).
** A more appropriate example is the Equalizer. It's possible for a [[JackOfAllStats Soldier]] to become [[FragileSpeedster super fast]] and [[GlassCannon do huge damage]] when wielding the melee weapon and [[OneHitpointWonder at low health]]. Obviously while powerful, using the weapon this way is very risky, as a casual shot could kill the soldier. Oftentimes cornered soldiers with no rockets use this tactic as a last resort.
** A sillier example is the close combat Ullapool Caber. Is it a giant log that takes health of the user when you swing it? No. It's a stick grenade, that you whack people with. It only works once, and you sure as hell are going to feel it if you don't have any bonuses because it explodes in your face. Despite the fact that you are dead if you come across another enemy, it's quite deadly, and can be useful as a last resort or for OHKOs with a critical charge.
** The Boston Basher for the scout is possibly his most powerful DPS weapon, having no damage penalty or crit penalty while being able to inflict bleed damage. However, any attacks that make absolutely no contact will instead hit you, inflicting full damage and bleed on you. On a crit, this can kill the wielder in one hit (although not instantly, but the bleed will do him in if he doesn't find a med kit). If combined with the Crit-a-Cola, this can turn the user into a whirlwind of pain, so long as they never miss.
** The Conniver's Kunai was designed with this in mind; it lowered the user's health so low that a glancing hit from any weapon was strong enough to kill the wielder. This is especially problematic because the class that uses it, the spy, is often in the midst of combat and very likely to get glanced even if the opponent doesn't know he exists. The perk comes that upon a successful backstab, the user gains all the health of the person he just killed. Skilled Kunai users can chainstab through an absurdly large amount of people that they can effectively tank sentries while this happens, which also helps that they also wipe out entire teams with this kind of a maneuver.
* 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 defeatable, 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.
* Multiple moves in the ''Franchise/{{Pokemon}}'' franchise harm the user (such as [[TakingYouWithMe Explosion]]), but these moves also tend to be very powerful.
** And then there's the move "Struggle," which is a rather weak move that damages the user by 1/4th of it's max HP. Chances are, you're only using it four times before you die.
** Focus Punch is extremely powerful, but at two costs. 1. It takes one turn to power up, leaving it open for attack. 2. If your pokemon is hit while powering up it "loses focus" and can't attack.
** And, of course, the classic Hyper Beam and all of its variations. It has 150 base power, but also renders the user immobile on the next turn.
** There's also Curse and Belly Drum, where the user sacrifices half its total HP in order to have the foe lose 1/4 HP every turn or maximize its Attack, respectively. If the user uses the former when they have less than half HP left, they faint; the latter fails when the user is at half HP or less.
** As of Generation V, there's a move called Final Gambit, which causes the user to deal its current HP to the enemy at the cost of fainting. It's also commonly [[SarcasmMode suggested]] as the best move for [[OneHitPointWonder Shedinja]].
** [[OverlyLongGag And then]] there's moves like Overheat and Close Combat, which, while powerful cause Stat drops to the user and leave them vulnerable to opposing attacks.
* 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.
* In [[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.
* 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.
* In ''VideoGame/ZettaiHeroProject'' Dangerama's entire skillset is composed of these. As a DeathSeeker, this makes sense.
* BloodMagic in the ''VideoGame/{{Dragon Age|Origins}}'' [[VideoGame/DragonAgeII games]]. It is ''extremely'' powerful and dangerous -- [[BloodyMurder to]] [[MindControl enemies]], [[PoweredByAForsakenChild allies]], [[CastFromHitPoints and the user]] -- and for many, many reasons, it is forbidden everywhere in the world. Even the Tevinter Imperium officially condemns BloodMagic, though in practice all of the Magisters are secretly Blood Mages.
** Though the [[WellIntentionedExtremist Grey]] [[KnightTemplar Wardens]] don't forbid blood magic.
* In ''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.
* ''VideoGame/DungeonCrawl'' has a lot of examples.
** Lugonu's self-banish causes permanent damage to HP and MP.
** As does Borgnjor's Revivification.
** Most necromancy is partially cast from HP.
** 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.
** Downplayed with mid-level summonings, most of which have a chance to be hostile.
* 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.
* An antagonist example: In ''VideoGame/GoldenSun'', shapeshifting into dragons seems to be a DangerousForbiddenTechnique 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 [[BalefulPolymorph forced]] on the antagonists of ''The Lost Age'', 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]]''...]]
* ''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.
** Epicac 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 Epicac 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.
** The Suicide Bomber vest 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.
** 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.
* 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.
* ''VideoGame/{{Ikaruga}}'': "Release the restraint device. Using the released power may result in [[ExplosiveOverclocking destruction of the ship]]".
* In the background lore for ''VideoGame/DiabloIII'', the Wizard character is doing this when he or she expands his/her arsenal to include [[PureEnergy the manipulation of raw mana]] and [[TimeMaster controlling time]], as well as when s/he ignores 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 Sorcer/ess of the past two games.
* 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.
* ''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.]]
** 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.]]
* In ''Franchise/TheElderScrolls'' {{Backstory}}, 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.
* A few heroes in ''{{VideoGame/Dota 2}}'' 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 explosions radius, if not kill them outright.
* In Darkest Dungeon, the Jester class has a move called Heroic End that would be better classified as a harmless forbidden technique. However in the Deepest Dark mod this attack gains incredibly high offensive bonuses against every status effect on the target. The catch is that if there are no status effects on the target it's not much better than a normal attack and using this move at all stuns, debuffs, and marks the user for 3 turns, ensuring anything that survives will focus their attacks on him and kill him before he recovers.

[[folder:Visual Novels]]
* 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.
** 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 spesifically gives him a clear limit on usage, and overuse will kill him. [[spoiler:Which it eventually does.]]
** 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.]]
* The protagonist of ''{{Tsukihime}}'' has the Mystic Eyes of Death Perception, which allow him 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.]]

* ''Webcomic/MSPaintAdventures'' and ''Webcomic/ProblemSleuth'' both feature '''SEPULCHRI-TUUUUUUUUUDE!!'''
** [[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."]]
* Webcomic/EightBitTheater":
** '''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.
** 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.
** 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.
* [[LastRes0rt Jigsaw Forte's Zombie Mode]], while not explicitly a DangerousForbiddenTechnique, 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.
* 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 at a time.]]
* There are several different levels of it in the WhateleyUniverse. Phase has a technique (using his disruption-light level on someone) that runs the risk of corrupting their Body Image Tempalte if they are an Exemplar or Shifter, and turning thme into something grotesque; he avoids it it on moral grounds. Fey has some spells powerful enough that the energy drain will destroy entire ecosystems around her, which is way worse.
* 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.
* 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.
* 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.]]

[[folder:Western Animation]]
* ''WesternAnimation/Ben10UltimateAlien'': Osmosians are aliens 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. To elaborate, [[spoiler:Kevin absorbed energy from Ben's Ultimatrix to stop Aggregor's plans of bringing forth the]] EndOfTheWorldAsWeKnowIt. [[spoiler:They defeated him alright, but afterwards Kevin went as far as ruthlessly kill whatever comes his way in a rampage out of insanity.]] He was so insane his wrongdoings can be classified as NightmareFuel.
* ''WesternAnimation/AvatarTheLastAirbender'': While it's not really forbidden, lightning redirection (a Firebending technique where you internalize lightning and shoot it in another direction) is extremely dangerous, to the point where even teachers of the move refuse to practice it with their students. 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. By the end of the series, only three characters know the technique, and only [[MemeticBadass Iroh]] is skilled enough to avoid the dangers consistently.
** [[spoiler: Energybending also carries the danger of mentally and spiritually destroying those who attempt to use it on others if their willpower isn't strong enough. This nearly happened to Aang when he used it on Ozai.]]
** [[spoiler: 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.]] [[spoiler:Like the Osmosian example above, it is shown that it is detrimental to the Waterbender's sanity, making them AxCrazy and power-driven.]]. To elaborate, [[spoiler: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.]]
* Later on in ''WesternAnimation/TheLegendOfKorra'', it's revealed that bloodbending has since been outlawed completely [[spoiler:and for good reason, as even after that its track record didn't get any better: Yakone came out to be an AxCrazy Bloodbender who brought fear to Republic City, and even figured out how to bloodbend without a full moon. Then came his sons, both of whom practiced bloodbending frequently and ended up insatiably power driven later on in their lives, especially Amon]].
* 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 Tuvok and Badka; 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.
* In ''WesternAnimation/{{WITCH}}'', the [[ElementalPowers Guardians]] can choose to transform into living embodiements 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]].
* ''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.
* ''Franchise/{{Transformers}}'' examples:
** 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.
** 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.
** G1 again, Windcharger can create magnetic fields capable of ripping apart even the strongest of metal structures. It burns him up very rapidly though.
** 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.]]
* 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.
* 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.
* 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.]]

[[folder: Real Life ]]
* Backfired with the destruction of HMS ''Invincible'' at Jutland. The DangerousForbiddenTechnique 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 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 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 a more volatile gunpowder than their German counterparts didn't help, either.
* The [[ExactlyWhatItSaysOnTheTin Mordhau]] 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]] that's forbidden, but that thing is heavy, and tends to ignore the fact the victim's wearing metal armor. It has that name for a ''reason''.
* 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.
* [[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 a similar retribution.
** Nukes are literally forbidden by international law; even ''threatening'' to use nuclear weapons against another power constitutes a war crime. Though eight nations are declared to have nuclear weapons (and 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.
** Even nukes aren't necessarily as repellant 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.
* 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.
* Overdosing on caffeine as a deadline draws nearer.
** 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.
* 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), 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''.
** See LimitBreak.
* Steroids, blood doping, performance enhancing drugs and other methods are illegal in most offical events, partly for ths reason.
* Water methanol injection, also called as War Emergency Power, on turbocharged internal combustion engines. Injecting 1:1 water-methanol mixture to the combustion chamber can boost the performance of the engine for up to 33% and add up extra horsepowers. Unfortunately, it 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 on breaking the seals.
** Likewise nitrous oxide injection, called [[BilingualBonus ''Ha-Ha-Gerät'']] in the Luftwaffe. It will boost the performance, but long periods of use will seriously damage the engine.
** 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.
** 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.