[[quoteright:347:[[Webcomic/ElGoonishShive http://static.tvtropes.org/pmwiki/pub/images/NanaseDeadlyUpgrade_6558.jpg]]]]
[[caption-width-right:347:[[http://www.egscomics.com/?date=2009-10-03 "You are willing to die for her. If you weren't... you would never have earned this spell.\\
Try not to die too quickly."]]]]

The human version of ExplosiveOverclocking. A hero, often one who is already able to transform into a [[SuperMode super-charged mode]], discovers, is granted, or reveals that he is capable of a further transformation which gives him unstoppable power.

This transformation [[PowerAtAPrice comes at great cost]], though, as, once he uses it, it's only a matter of time before he [[YourDaysAreNumbered dies]], [[SuperPowerMeltdown explodes]], [[WithGreatPowerComesGreatInsanity goes insane]], [[SuperpoweredEvilSide becomes a mindless super-powered beast]], or [[AscendToAHigherPlaneOfExistence ascends to a higher plane of existence]]. Even if it doesn't kill him, he still may have to [[CastFromHitPoints use his own life force to attack]].

[[GodzillaThreshold When forced to pull it out]], the hero's friends will often try to talk him down, if uses it anyway it might result in a HeroicSacrifice.

Often, the extreme bodily stress will be demonstrated by the character [[PainfulTransformation being in incredible pain during the transformation]].

Sub trope of SuperMode. Compare HeroicRROD, MySkullRunnethOver, PhlebotinumOverload, GoingToGiveItMoreEnergy, DangerousForbiddenTechnique and PowerUpgradingDeformation, which has ugliness as the tradeoff.


* The Kaioken technique from ''Anime/DragonBallZ'' [[InformedFlaw supposedly]] risked permanent damage to Goku's body whenever he used it -- especially when he overclocked it. However, thanks to MyKungFuIsStrongerThanYours, by the time he's fighting against Frieza, he can multiply it by twenty-fold with fairly limited drawbacks. [[spoiler: By ''Anime/DragonBallSuper'', Goku learns to combine Kaio-Ken X 10 with the Super Saiyan Blue form, but as this combo is still a work in progress it initially only has a 10% succes rate, with the other 90 spelling severe injuries or even death.]]
** Super Saiyan 3 is another example; a few minutes of use drained Goku (who was dead at the time, but who was given 24 hours of life force so he could visit his family) of about 12 hours of his life force, and Gotenks, who burned out his 30 minute fusion in 5 minutes. Goku eventually manages to mostly iron out this flaw, but by the time he does Super Saiyan 3 has become SoLastSeason.
*** Brought up once again in the Future Trunks arc of ''Anime/DragonBallSuper''. It's revealed that the Kai's Fusion earrings are [[spoiler: only permanent for Kais. For mortals the fusion lasts 1 hour (which was the real reason they defused when absorbed by Super Buu). Super Saiyan Blue Goku and Vegeta use them to form Vegeto Blue, but the combination burns so much energy that the fusion lasts only about 5-10 minutes.]]
*** Also from the Future Trunks arc. The fusion between [[spoiler: Goku Black and Zamasu]] is literally a deadly upgrade for the latter. He is immortal, but the other half is a mortal. By fusing with him it means that his body is now half mortal, thereby making him mortal and finally killable - albeit insanely powerful and still nigh-invulnerable.
** ''Anime/DragonballGT'' reveals that by taking control of the transformation into an ape, a Saiyan can reach Super Saiyan 4, which Goku and Vegeta can maintain ''without'' exhausting themselves. However, the real problem comes when they perform a FusionDance into Gogeta against Omega Shenron, who has enough power to waste their galaxy if he wanted. Gogeta can use ''both'' Goku's and Vegeta's deadliest attacks ''[[AllYourPowersCombined as one]]'', the first hit knocking out Omega Shenron's stolen Dragon Balls, and the second would've ''killed'' the weakened Syn Shenron... but he's too much of an idiot clown to do the job soon enough. Instead, he forgets the fusion will only last 30 minutes, and wastes precious time screwing with the dragon on ''[[WhatAnIdiot cheap parlor tricks.]]''[[note]]It wasn't a goof-off waste of time. He was purposefully acting that way in order to get Shenron to use his negative karma attack so that he could reflect it and convert it into a positive karma attack, thereby dispelling the cloud surrounding the Earth. It just took too long to get that job done before "getting serious".[[/note]] When Gogeta ''does'' try to execute the final blow... [[EpicFail the fusion comes undone...]] with less than ''[[OhCrap ten]]'' minutes elapsed. And they ''[[CurbstompBattle pay]]'' for it...
* ''Manga/DGrayMan'': Every exorcist has a synchronizing rate with their empatheticWeapon. If they force their innocence to go over this rate, they can gain a power boost but their bodies break down and they suffer a HeroicRROd.
* ''Manga/InuYasha'''s transformation into his [[SuperpoweredEvilSide full-demon form]]. His demonic blood devours a little more of his mind every time, so his demonic form becomes more and more uncontrollable. When he first transforms, he sounds like Inuyasha on a ''really'' bad day, but by the end of the series his full demon form is incapable of speech and Kagome is unable to snap him out of it.
** And as an inversion, he can also transform into human form during the nights of the New Moon. What makes this a "Deadly Downgrade"? Simple; in human form, he loses all of his demonic powers, meaning he's easy prey for any of the demonic enemies he's made in his life... or, indeed, any true demon that realises what he is, as half-demons are almost universally despised by their full-blooded kindred.
*** Furthermore, he only transforms when facing down enemies it would take him literally seconds to kill with full power. These episodes are usually both awesome and frustrating. His human form can sometimes fall into NotCompletelyUseless as well, as being a human allows him to circumvent and NoSell things that would be dangerous or otherwise lethal to anyone with demonic blood, such as the demon purifying barrier of Mt. Hakurei. He's still got all the disadvantages of being mortal, but it's saved his bacon more than once.
* Almost every extremely powerful technique in ''Manga/{{Naruto}}'' is some version of this.
** The various stages of Naruto's Jinchuriki transformation, from Versions 1 and 2, to Partial Transformation, to Tailed Beast Mode all involve the Fox's influence gradually taking over Naruto's mind, body, and soul. If he goes past the 4-Tailed form, nothing but the words of encouragement from his father and can save him from the Fox's wrath. This also lessens Naruto's lifespan, not that that matters when he's the descendant of a clan known for its natural longevity. [[spoiler: Naruto eventually tames Kurama and gains access to [[HourOfPower five minutes of using Kurama's maximum power]]]].
** Naruto's upgraded Rasengan, the Rasenshuriken, is basically a magical fletchette bomb that attacks targets at a cellular level, inflicting massive and very hard-to-heal damage. Unfortunately, since it's held in the hand, [[LogicalWeakness it does this to the user as well]]. [[spoiler: Naruto removes this weakness by perfecting the technique to the point where he can throw it, getting it far enough away from himself that he isn't hit by it.]]
** Tsunade possesses a technique that allows her to instantaneously regenerate, but it also speeds up her cell division and shortens her lifespan. She is also a descendant of the Senju/Uzumaki clans, so how much this actually matters is currently unknown.
** ''Naruto'' also has Rock Lee, whose power revolves solely around the DeadlyUpgrade, in that he can open up certain chakra gates to gain large power boosts at the expense of damaging his body. The more gates he opens, the more injured he becomes, and if he were to open up all gates, he would become extremely powerful for a short time and then die.
*** Might Guy [[spoiler: uses all the gates at one point, giving him strength and speed surpassing even [[SuperMode Tailed Beast Mode Naruto]] only to collapse into a pile of ash and bone fragments once all his energy reserves are used up. The end result was avoided with Naruto's HealingHands.]]
** Choji's Three Colored Pills each give as successive boost in Chakra, but burn out the user's body. The final, red pill instantly burns all the fat from his body and converts it to energy, but nearly kills him in the process. It would likely be fatal to anyone who's ''not'' as fat as he is. The pill also causes the user's cells to break down. When he takes it, he nearly dies and is only saved by intensive medical care and medicine from the Nara clan.
** Simply implanting Hashirama Senju's cells into a person's body can grant them enhanced regeneration and sometimes even the ability to use his Wood Release techniques. However the cells can grow explosively if not properly controlled, transforming living flesh into a tree.
** The Mangekyo Sharingan will eventually render its user blind and result in extreme fatigue. Excessive use of Amaterasu can cause the user's eye to bleed. Sasuke was nearly rendered blind after he used it liberally in a misguided RoaringRampageOfRevenge. The only fix is to take someone else's Sharingan and implant them as your own.
*** Izanagi will grant the user a moment of NighInvulnerability, but permanently blinds the Sharingan used. Only the regenerative nature of Hashirama's cells can allow it to see again.
** Orochimaru's Curse Seal allows the person to use more chakra, and increases their attack power, but using for too long will corrupt them and the seal will completely take over. Sasuke was unusually capable of controlling this [[spoiler: and the otherwise unstoppable transformation of the person from whom the Curse Seal originated. But now Sasuke seems to have lost the Curse Seal in his fight with his brother.]]
** In the fillers, Kagerou's Ephemeral Vengeance technique seemingly shortens her lifespan, [[spoiler:even though it is not what kills her]].
** Pain ([[spoiler: Nagato]]) used the Demonic Statue to suck out the souls of Hanzo's men, which emaciated his body. Later, Pain's jutsu that destroys much of Konoha shortens his lifespan. Even just maintaining his HiveMind and using any of his jutsu wrecks havoc on his ''real'' body. According to Konan, he's in danger of dying due to overexerting himself in his battle with Naruto. [[spoiler: This might be why he follows "Madara" despite his own incredible power.]] Then he uses a jutsu to [[spoiler: DisneyDeath revive everyone he killed, and this ages him to death. He only gets to revitalize his body after death in Edo Tensei, using the Preta (Hungry Ghost) Path's powers to suck in Killer B's Version 2 chakra, reversing his transformation.]]
* People who possess the ''Manga/DeathNote'' in the anime of the same name can give up half of their remaining life span to gain the ability to discover the true name (which, [[MagicAIsMagicA by the rules]], they need to know to kill a person) of anyone whose face they can see. An even larger downside is that if they lose their Death Note, they lose the power-- but also the half of their remaining life they sacrificed. If they find their Death Note again, they have to sacrifice half of their remaining life again to regain the power, meaning they'd only have 25% of their original remaining life span left.
* In ''Manga/ThePrinceOfTennis'', no-one's life is literally in danger, but junior high tennis is [[SeriousBusiness taken very seriously]], so permanent physical damage may well be equal to death, or [[FateWorseThanDeath even worse]].
** One of the earliest example is the Hadoukyuu, a powerful shot that hurts the arm of whoever hits it, as well as whoever is bold, or stupid, enough to try to return it. Used initially by Ishida Tetsu, who then passes it on to Kawamura Takashi, who develops a Dash version which is even more destructive. Then we meet the big brother of Tetsu, Gin, who has [[OneHundredandEight 108]] levels of this move, of which level ONE is equal to the Dash version. Despite this, Gin loses to a fluke which is widely seen as [[MyKungFuIsStrongerThanYours a cop out]].
** Tezuka Kunimitsu, widely regarded as one of the best players in the series has several {{Deadly Upgrade}}s. The Zero-Shiki Drop Shot and the Invincible Tezuka Zone place considerable stress on his left arm, but he still manages to go into a 37-35 tiebreaker, which is ridiculous for tennis. Later on, these both get upgraded into a serve version, making it literally unreturnable, and a Reverse Zone, which places SIX times the burden on his arm, making it bleed a deep purplish hue by the end of the match. Obviously, none of his teammates want him to sacrifice his arm for the sake of victory, seeing that he has a promising professional career in his future. Ironically, in the matches where these are first unveiled, he loses, creating blots on an otherwise perfect official record.
** Another ridiculous technique will ruin one's shoulders, since these players have only hit puberty, and their bodies are still maturing. Yet another one ruins the player's legs, because he's been running at hyper speeds. There's even a player who literally becomes a devil, complete with bloodshot eyes and newly-turned-white hair.
** The most ridiculous example of this trope is the Pinnacle of Perfection, which appears to take the player who achieves this state to a higher plane of existence, but at the cost of losing all of his memories, including those of how to play tennis, rendering this upgrade, at face value, essentially useless. Currently, not surprisingly, the main character is believed to have obtained this state, seeing as how the manga is finally coming to an end. However, it turns out the Pinnacle of Perfection has no drawbacks. It is revealed that Ryoma used it during his match with Kintarou, before losing his memories. Losing his memories was because of an accident, not because of the Pinnacle of Perfection.
* ''Manga/OnePiece'':
** Tony Tony Chopper (a reindeer who can become a humanoid with the power of the Person-Person Fruit) can access four additional forms besides his animal, human, and hybrid forms with the use of pills called "Rumble Balls". However, if Chopper takes more than two Rumble Balls within six hours, he turns into a mindless hulking monster. Not only is this move dangerous to those around him (due to his mindless rampaging), but it causes internal bleeding (shown by the blood coming from his mouth, despite never being harmed), making it lethal for himself as well. It's because Chopper's Monster form requires massive amounts of energy to keep going, far more than Chopper actually has. In addition, Chopper is essentially unconscious while he's in that form so he can't leave it on his own. After the TimeSkip, he learned how to control it, but it still renders him too weak to move after using.
** Gear Second not only drains Luffy's stamina faster than normal, but according to Rob Lucci, it shortens his lifespan by increasing his metabolism. Lucci also states that if Luffy were not a rubber man, his heart would explode if he used the technique. Of course, if he wasn't made of rubber, he probably couldn't do it in the first place. It is likely that similar to Chopper above, his greatly increased stamina after the TimeSkip renders these limits moot.
** And way before all that, in Alabasta arc, Kicking Claw Squad is a very {{anvilicious}} parody of this trope: four royal guards take an elixir that greatly increases their power but will kill them in a matter of minutes... And the BigBad refuses to fight them, instead retreating and waiting for them to die.
* In ''Anime/DigimonAdventure'', when Greymon was pushed by Taichi into evolving, he changed into the dark [=SkullGreymon=], a mindless monster. When he evolved "naturally", he became his true Perfect form, [=MetalGreymon=].
** Takato in ''Anime/DigimonTamers'' had a similar experience: When [[spoiler:Beelzebumon kills Leomon]], Takato's rage and grief is so intense that it corrupts [=WarGrowlmon=]'s evolution and he becomes Megidramon, which would be fine, except Megidramon's power is ''so'' great, that it begins to destabilize the fabric of the Digital World. It's not until Takato gets a hold of himself that Megidramon devolves back into Guilmon, and together, they [[FusionDance Matrix Evolve]] into Dukemon/Gallantmon.
** In ''Anime/DigimonFrontier'', the Beast Spirit evolutions ended up being [[DeadlyUpgrade Deadly Upgrades]] in a sense because the kids couldn't control the power at first and went berserk, wrecking areas and nearly killing each other. Of course, they eventually got over this problem. Only Zoe and [[spoiler:Koichi]] were able to control their Beast Spirits right away ([[spoiler:in Koichi's case, when he gained his true Spirit forms]]).
** ''Anime/DigimonSavers'' and its associated tamagotchi introduces Burst Mode, a DeadlyUpgrade version of Season 2's Mode Change. In the tamagotchi, if the Digimon runs out of "Burst Points," it dies. [[spoiler: In the anime, Masaru combines Takato and Taichi's mistakes, and mis-activates Burst Mode, changing his partner [=ShineGreymon=] to Ruin Mode, who quickly ran out of energy and died. Though, since the Minions of [[StoryArc The Arc's]] BigBad died first, he got better.]]
* Ichigo in ''Manga/{{Bleach}}'' is able to throw around massively powerful ''kuroi getsuga tenshō'' energy blasts, but doing so too often risks losing his personality to his [[SuperpoweredEvilSide Hollow side]]. He can allow his Hollow side to come out in times of distress, whose violence and power is usually enough to annihilate any opponent. After training with the Vizard, he can even do so without going [[SuperpoweredEvilSide evil]], but only for eleven seconds.
** And in recent events, it's revealed that he's [[spoiler: transformed into a sort of Super Hollow, capable of defeating Ulquiorra easily. However, evidently he's gone completely berserk, and has (at least temporarily) given in to his Hollow side]].
** [[spoiler: Ichigo eventually learns the Final Getsuga Tensho, the final form of his zanpakuto which surpasses even his Bankai. He puts it to use in his final battle against Aizen, allowing Ichigo to defeat him. The downside of this power is, once he uses it, he loses his Shinigami powers permanently]].
** Meanwhile, [[spoiler:Ishida's final "upgrade" is one-use-only. He removes his 'Senrei' gloves, which make it more difficult to collect spirit particles- therefore someone who can collect the normal amount of particles while having the glove on has reached the pinnacle of Quincy power. When the gloves are removed that limit is removed, so a much greater amount of particles can be collected. However, this amount is far too much for his body to handle, so his body [[BroughtDownToNormal seals his powers altogether]]. He gets his power back later, though, by pushing himself to exhaustion so that being shot near the heart reopens the paths to his power. This leaves him with a Quincy "cross" shaped scar where the arrow struck.]]
** Cirucci Thunderwitch gains the ability to bypass her released form's drain on her spiritual by discarding her wings, enabling her to use a large energy sword from her tail at the cost of never being able to use her wings again.
** The ultimate technique of Komamura's clan, [[spoiler:the Human Metamorphosis technique, temporarily grants them an immortal human body]]. To perform the technique, they have to cut out their own heart. [[spoiler: It, too, is one-use only, leaving the user a mortal non-anthropomorphic animal.]]
* EVA-01 and EVA-02 in ''Anime/NeonGenesisEvangelion'' were given strength and capabilities in accordance to the Sync Ratio between the pilot and machine, but the higher the values, the more likely that the pilot might [[{{Synchronization}} suffer the injuries the mecha did]], go insane, or [[spoiler:get absorbed into the mecha]].
* Franchise/SailorMoon can transform into Princess Serenity and blow the BigBad away with her [[AppliedPhlebotinum silver crystal]] and ThePowerOfLove... but she dies every time from all the energy output.
** In the live-action ''Series/PrettyGuardianSailorMoon'', she can upgrade to Princess Sailor Moon, in which she is possessed by Princess Serenity and has access to great power. Unfortunately, Princess Serenity is something of a sociopath in that series that doesn't care if she hurts anyone to kill the monster of the day, constantly plays a harp that is actually feeding the energy of Queen Metaria and accelerating the destruction of the planet, summon monsters to beat the crap out of her friends when they try to stop her, oh, and she's perfectly happy to ''destroy the world and kill everyone on it'' if anything happens to her lover. Needless to say, this makes Princess Serenity as much of a threat as the Dark Kingdom at the end of the series.
* The anime ''Manga/{{Claymore}}'' almost entirely revolves around the caveat that when the series' eponymous half-demons overclock their powers too far they turn into monsters far more dangerous than those they were created to destroy; some of the more powerful of these 'awakened ones' are the primary villains of the series.
** However, Claymores who have gone past their limit and managed to return to normal are able to do so more easily, allowing them to use more of their power, provided they don't go TOO far past their limit. However, it's theorized by said Claymores that they may still be awakening because of it, just very, very slowly.
* The ''[[Anime/MegaManNTWarrior Rockman.EXE]]'' anime series did this in their final two seasons, with a twist - Rockman didn't control his transformation, a child named Trill did. Sometimes this worked out, like when Rockman was fighting the very giant Cyber Beasts he was drawing his transformation from, and sometimes it didn't, forcing the other characters to devise a complicated plan to capture him and settle him down which usually failed several times.
** The parallel game, ''VideoGame/MegaManBattleNetwork 6'', played with the same mechanic. In battle, you can take the beast form for three turns, after which you drop into a weakened, untransformed state. Of course, you can do it again, which puts you totally out of control and attacking randomly, and if ''that'' doesn't win you the battle, you go into a state so tired and weakened that you have to continue the battle at a pretty significant disadvantage. Of course, it doesn't stop the writers from arranging chapters where Mega Man is forced into uncontrolled transformation and you have to lug some other character over to put him down and get him back to normal.
** In 4 and 5, the player can gain certain "Dark Chips". They are a variation of normal chips (there's Dark Fan, Dark Vulcan and so on), but with immense power and ability to change the tide of a fight. There are, however, two drawbacks. One is that every time Mega Man uses the chip, his HP lowers by 1 permanently. Also, the more he uses Dark Chips, the faster he will be placed under "Dark Mega Man" state. He becomes a super-powerful rampaging machine that randomly uses Dark Chips, moves chaotically and doesn't stagger when being hit, but he also slowly loses HP until he reaches 1, at which point he goes back to the normal state. The only saving grace for 4 is the ability to have multiple playthroughs, so you can recollect HP upgrades and basically negate the HP downs. It's made a bit better in [=BN5=], where you sacrifice a chip of a certain type to go into a cross form, but using them regularly will permanently shave 1 HP off your max limit per use.\\
Later on, Mega Man gets the ability to do this with Dark Chips. Chaos Unisons (as they're called) allows Mega Man to use (most) effects that he can use in a regular Cross, with the addition of being able to use the Dark Chip sacrificed as a ChargedAttack. Fail the charge, though, and Dark Mega Man will show up-- on the enemy's side. In addition, you only have the ability for one turn, the failure window for the charge doubles each time you use the Dark Chip, and you lose the ability to use the corresponding normal Cross for that battle. [[GameBreaker And then you realize the charge releases instantaneously if you let go of the fire button while the game is paused, and you can see what state the charge is in...]]
* In ''Manga/RaveMaster'', Sacrifar, the appropriately-named 9th form of Ten Commandments sword bestows the wielder with overwhelming power, at the cost of being gradually consumed by the sword both physically and mentally. At its first appearance, there is quite a bit of LampshadeHanging over how crazy the man who forged the sword was to put in that form.
** A member of the Dragon Race (like Let, Julia, or Jegan) can invoke the great power of the Dragon God, but only by sacrificing their lives to the deity.
* The lead character of ''Franchise/MagicalGirlLyricalNanoha'' has a tendency to do things that are really bad for her, especially in the second series. This goes from using the dangerously explosive Cartridge System to using her WaveMotionGun's full-power form, Excelion Mode. It's revealed in the third series, ''Anime/MagicalGirlLyricalNanohaStrikers'', that [[spoiler:at some point during the TimeSkip this all caught up with her, and what should have been a [[OnlyAFleshWound minor injury]] in battle caused such extensive damage that she had to spend months learning to walk again.]] She later has her Excelion Mode replaced with a weaker Exceed Mode, which is a more traditional SuperMode. At the end of the series, however, she deploys a new Blaster Mode, which [[CastFromHP causes direct physical damage to herself and her weapon as a result of drastically boosting her power]]. Of course, by the time she receives this, she already has a known tendency to use techniques and upgrades that pushes her body to the breaking point, so instead of telling her not to use it, her [[TheLancer long-time partner]] tells her not to ''over''use it.
* In ''Anime/YuGiOh'', the Spell Power Bond can double the attack strength of any Machine-type Fusion monster; however, at the end of the turn in which it is used, it decreases the user's Life Points by the original attack power of the monster. Possibly another example of ExplosiveOverclocking. Similarly, the Spell Limiter Removal can double the attack strength of all the user's Machine-type monsters for one turn. After which, they are destroyed.
* In ''Anime/{{Witchblade}}'' anime use of Witchblade is shown as too taxing for a human body, and wielder of a Cloneblade sooner or later [[PhlebotinumBreakdown falls]] a victim to rapid and irreversible body deterioration ending with spectacular SuperPowerMeltdown. In some cases it will also corrode their mind as well. Both original and {{Evil Knockoff}}s are {{Clingy MacGuffin}}s, of course.
* In ''Manga/OutlawStar'', the three rare Caster Shells, numbered 4, 9, and 13, are so powerful that it also takes away part of Gene Starwind's life whenever he uses it. On a side note, 4 and 9 are considered unlucky numbers in Japanese culture, and 13 is an unlucky number in western culture.
* Guts from ''Manga/{{Berserk}}'' has the Berserker's Armour, which draws out the full physical strength of the wearer. However, the armour also draws out the SuperpoweredEvilSide of whoever wears it, and while the wearer can ignore pain, this is a double-edged sword, since the strength of whoever wears the armour will badly damage their body. Also, the armour mends broken bones by ''piercing through flesh with spikes''. This led to the previous owner dying of blood loss after every single bone in his body was broken.
* Upgrading one's Alter Power in ''Anime/SCryed'' includes the risk of not only dangerously messing up the user's body, but also eventually draining the user's entire life force. As the series goes on, the Upgraded Alter Power users show more and more damage to their own bodies from continual use. Kazuma and Ryuhou show scars across their bodies where their Alter Powers bond to their bodies, while Straight Cougar is actually ''unable to walk properly because of how messed up his legs are.''
* ''Manga/{{Hellsing}}'':
** Alexander Anderson uses the Nail of Helena on himself and becomes [[spoiler:a plant-thing far more powerful than his normal self]] but using it requires him to stab himself in the heart.
** Likewise, [[spoiler:[[FanNickName Dark Walter]] is vastly superior to his elderly, human self in terms of speed, dexterity and skill (he's able to slice a [[UpToEleven skyscraper in half]] at one point). But his endurance for prolonged combat is quite poor as he quickly develops an IncurableCoughOfDeath very soon after engaging Alucard in battle, due to the fact that his [[BodyHorror body is breaking down because of the Doctor's hasty surgery]].]]
* In ''Manga/MahouSenseiNegima'', Negi learns a BlackMagic version of this. He gets to equip spells to his body to boost strength and/or speed, depending on what he equips, at the cost of damage to his ''soul''. The arc's BigBad refers to it as "magical doping".
** His master later reveals that [[spoiler:its turning him into a demon.]] He is almost eerily nonplussed by that revelation, something he handwaves by pointing out that, technically, his master is [[spoiler: a demon]], and she's still a good person.
** [[spoiler:Chao Lingshen]] also has one of these, in the form of magical runes carved on her body that release a titanic magical power when unlocked. However, doing so causes her intense pain whenever she casts something, so they're normally sealed. Akamatsu has stated that it's in some way related to the BlackMagic Negi's later uses.
* In ''Manga/FairyTail'', Natsu consumes the [[spoiler:Etherion magic absorbed by the Tower of Paradise]]. This brief and HUGE power boost gives Natsu the edge he needed to give the [[spoiler:fake]] BigBad Jellal a beatdown. But at the start of the following arc Natsu suffers narcolepsy due to consuming non-fire related magic.
* In ''Manga/KenichiTheMightiestDisciple'', there are two kinds of aura used while fighting: Dou (letting your anger burst out) and Sei (keeping a calm and level head). It's possible to combine the two for more power, but doing so rips apart the muscles and puts heavy strain on the mind. Of the two who've used it, one ended up in a wheelchair. The other one [[spoiler:died, but for unrelated reasons.]]
* In ''Anime/TekkamanBlade'', D-Boy/Blade's constant transformation from human to Tekkaman and back is disintegrating his central nervous system (the other human-based Tekkamen were also going to die as a result of incompatabilities). When he gets his SuperMode upgrade, in at least the Australian version "Teknoman", the main villain comments that this upgrade causes death within a few months, and it is shown to cause D-Boy/Blade to lose memories as a result of transformation instead of having its previous deletorious effect on the central nervous system.\\
So long as a Tekkaman was fully converted with an intact crystal then they could switch between forms with no penalty. The problem was that early on in the series D-Boy's crystal was broken and although the shards were placed on Pegas to allow transformation it was flawed and and repeated use of the flawed transformation was what caused nervous system damage to him. It also meant that so long as he used the broken crystal he'd have a time limit before going berserk. It was also true that if a human and Tekkaman plant weren't completely compatible, then they'd eventually die (which is what happened to D-Boy's sister).
* In ''Manga/{{Mahoromatic}}'', combat android-turned-maid Mahoro has an Ultimate Attack that is actually fueled by her life-force, so every use of it shortens her already brief lifespan.
* Subverted in ''Manga/DragonHalf''. Mink's power grows constantly when she passes her metamorphosis, due to be a red dragon/human hybrid. However, if she achieves her maximum might and completes her metamorphosis, a prophecy states that "a black monster shall appear". A magic bracelet allows her to stop her power development at will, but against the stronger enemies she keeps facing, she is forced to [[TimeToUnlockMoreTruePotential unlock more potential]]. When she finally unleashes all her power to save her true love, the transformation comes? The black beast finally is showed in front of them all. [[spoiler:As a tattoo on Mink's butt.]]
* Using the black blood in ''Manga/SoulEater'' is this, as the advantages given by that kind of madness (hardening the blood against injury, not caring about injuries you're receiving or giving because you're out of your mind) are negated by the consequences of doing so too much; the insanity could become permenant. Currently the heroes have gotten around this by being able to control insanity for their own uses. Whether this trick will continue to work remains to be seen.
** The Nakatsukasa Purpose is originally seen to be this, but only because Black Star was going about using the Demon Blade mode the wrong way. Until he was beaten into re-thinking his approach, he was told explicitly that over-using the Forbidden Technique would kill him. Once Black Star faces the will inside the Demon Blade and declares that he will strive on the path of warrior to resolve the despair of fallen warriors, he became capable of using the mode without issues.
** Kid's Sanzu Lines ''could'' be an example of this. Fanon speculation holds that he will get the upgrade that would prove deadly to his father. If so, Shinigami is remarkably (well, not so surprising coming from him) upbeat about the prospect. As of defeating Noah with this Super Mode, Kid appears aware of the Lines connection to his [[TrulySingleParent father]], but does not seem to know what effect the temporary upgrade has on Shinigami. [[spoiler: Now confirmed, Shinigami died. Now Kid is in danger of [[WithGreatPowerComesGreatInsanity succumbing to the Madness of Order]]]]
* Speaking of blood, [[SuperhumanTransfusion vampire blood]] in ''Manga/RosarioToVampire'' is this to a human (Tsukune) who receives it. First, it either heals the recipient's body completely or kills him, which already makes it [[EmergencyTransformation a last resort]]. Then, it [[HourOfPower temporarily]] gives him the powers of a vampire, but after so many uses, the change becomes permanent. Unfortunately, the blood gradually breaks down his body and mind from within, and had its progress not been stopped by a PowerLimiter, he would have been turned into a [[TheBerserker rampaging]] [[OurGhoulsAreCreepier ghoul]]. It still surfaces occasionally.
* [[BewareTheNiceOnes Cho Hakkai]] from ''Manga/{{Saiyuki}}'' can turn into a nearly unbeatable super-powered youkai by taking off his [[RestrainingBolt power limiters]]... but runs the very real risk of "losing himself" to the Minus Wave that's [[BrainwashedAndCrazy brainwashing]] weaker-willed youkai.
** And the same goes for Son Goku of the same series, much like the ''Franchise/DragonBall'' example above-- fitting, since they're based on the same character from mythology.
* In ''Manga/YuYuHakusho'', Hiei's [[DangerousForbiddenTechnique Dragon of the Darkness Flame]] goes given a second use beyond basically an out of control beam attack- Hiei can let it hit him in order to absorb its power. The catch to this powered up state? It leaves him utterly drained and basically comatose for a time. Good thing he's got teammates to look after him.
* ''Anime/BraveCommandDagwon'' has Daidouji En becoming Super Fire Dagwon only 3 times due to this. That form, while immensely powerful, requires a burst of energy from the Dagbase to even start the combination and is basically the equivalent of one person controlling two bodies - it eats up the user's stamina like nothing else. He's tough and a walking embodiment of willpower, but it still left En in a hospital bed after each use.
* [[spoiler: Edward]] uses this in ''Manga/FullmetalAlchemist.'' After receiving a massive injury during a fight, he [[spoiler: uses his soul as a mini-Philosopher's stone, stopping the blood loss in exchange for a few years of his life]].
** Toward the end of the [[Anime/FullMetalAlchemist 2003 anime]], Al [[spoiler:becomes a Philosopher's Stone]]. After that, any use of alchemy costs him a piece of his body.
* In ''Manga/AyashiNoCeres'', the villains have developed some sort of serum to activate/boost the powers of potential ten'nyo, but once someone is injected with it their body begins to break down,a process that seems to be accelerated by frequent use of ten'nyo powers.
* In ''Anime/PuellaMagiMadokaMagica'', [[spoiler: becoming a MagicalGirl grants you magic powers, but the more often you use them, the faster you fall prey to TheCorruption and eventually turn into a witch. The only way to avoid that fate is to die before it happens.]]
** [[spoiler:Madoka]] is an extreme example of this, having been repeatedly buffed by [[spoiler:a time-travelling Homura]] to the point that activating her powers even once would cause her to become [[GodzillaThreshold Godzilla's worst nightmare]] moments afterward. [[spoiler:She eventually subverts this by making a contract specifically to erase all witches from every point in every timeline--including the one she'll become.]]
* ''Manga/OtogiMatsuri'': The power granted by the Phoenix-like god named Suzaku is a mystical bow that appears as an extension of Yousuke's arm, that fires arrows of light with the power to kill evil spirits in a single shot. In exchange, Suzaku declares that it will take Yousuke's "future"... meaning that the young man only has a year left to live.
* [[spoiler: Break]] from ''Manga/PandoraHearts'' has this. [[spoiler: The more he uses his [[EldritchAbomination Chain]], the more it destroys his body...he's already gone blind and has repeated moments of BloodFromTheMouth.]] And yet, he's still [[HandicappedBadass extremely badass]].
* In ''Anime/KillLaKill'', protagonist Ryuuko's [[ClothesMakeTheSuperman sentient uniform, Senketsu]], enhances her physical strength, durability and agility to superhuman levels, but constantly drains her blood to the point of unconsciousness, [[spoiler: until she stops subconsciously rejecting the embarrassingly {{Stripperiffic}} outfit at which point the disadvantage is negated]]
** Antagonist Satsuki gains the same powers but is able avoid this drawback due to knowing how the godrobe works and [[spoiler:having no shame]], later in the series however [[spoiler:we learn that using the godrobe for long periods takes an enormous toll on her health which she has been suppressing by sheer force of will]]
** In the final episode [[spoiler: Senketsu absorbs the power of "Absolute Domination" becoming supremely powerful at the cost of overloading and being destroyed shortly afterwards]]
* In the first ''Anime/TenchiMuyo'' movie, ''Tenchi Muyo In Love'', Achika (Tenchi's mom in the ''Anime/TenchiUniverse'' continuity) ends up unlocking her Juraian powers, then proceeds to blow it all striking down KAIN. This ended up cutting her lifespan so much that she dies when Tenchi is only 3.
* ''Manga/JojosBizarreAdventure'' has a few. One of the most notable is in Part 2: Wamuu's final attack, "Converging Squall", draws air in and out of tubes in his chest, creating razor-sharp winds that hit everywhere around him. However, the friction created by this attack slowly tears his body apart from the inside. Wamuu only dares to use it against Joseph after already losing his arms and taking a Hamon blow to the chest, which will kill him anyway if he doesn't finish the fight in minutes.
* In ''Manga/HunterXHunter'' [[FunctionalMagic Nen]] is an example of ConditionalPowers. The greater the restrictions placed on a Nen user, the greater the power. [[spoiler:Main character Gon]] crosses the DespairEventHorizon during the Chimera Ant Arc and, in his own words, "uses everything" to make himself strong enough to crush the one who pushed him over the horizon. At the cost of never being able to use Nen again and an extremely shortened lifespan, he is temporarily aged to adulthood and gains Nen that rivals the Chimera Ant King's.
* In the anime adaptation of ''Manga/MagicKnightRayearth'', Alcyone tricks Ascot into giving this to one of his pet monsters. It hugely increases its power and freezes the whole landscape, but before long it turns it into a small iceberg with PowerIncontinence and it eventually shatters. Ascot is ''not'' happy.
* The Griselda and Libertus Hyper-Zoanoids are this in ''{{Manga/Guyver}}''. Libertus are designed to rip through other Hyper-Zoanoids like tissue paper while Griselda can, at short ranges, over-power the telepathic control of a Zoa''lord''. However to power those abilities they need to spend most of their time in nutrient tanks because there's no other way to absorb enough energy and even with that the stress on their systems is slowly killing them. (Predicted survival time is about two years).
* ''Manga/AttackOnTitan'' reveals that [[spoiler: consuming the cerebrospinal fluid of a Titan Shifter allows someone to become one themselves. Unfortunately, once this happens, they have only 13 years left to live. Their human bodies gradually break down until they die, complete with BloodFromTheMouth.]]

[[folder:Comic Books]]
* This is the key premise of ''ComicBook/StrikeforceMorituri''. The process that grants humans super powers against the AlienInvasion ensures that the empowered humans will also die within a year (if not sooner).
* In ''ComicBook/XMen'' related comics (her first appearance was in ''ComicBook/XFactor'') "Infectia" was a woman whose whole power ''was this trope.'' Specifically, she could mutate other people into having superpowers, but then they died within 24 hours.
* Citizen Solder from ''[[ComicBook/{{Stormwatch}} Stormwatch: Team Achilles]]'' had the power to grant a particularly deadly version to others: twenty ''minutes'' of superpowers, then they die. Essentially, he made superhuman suicide bombers.
* In a ''ComicBook/SpiderMan'' arc, the Vulture was dying of cancer; feeling there was no need to worry about safety anymore, he set his flight harness to max levels that he never dared set them to before, making himself far stronger and faster than he ever was. (He almost ''did'' kill himself in the process, and nearly took Spider-Man with him as he did. It was implied that one of the biggest reasons Spidey saved him was to make him apologize to his Aunt May, who he had threatened during his RoaringRampageOfRevenge.)
* During the post-''ComicBook/{{Convergence}}'' stories, ComicBook/{{Superman}} went through two close-calls - becoming a God after the death of Darkseid during the ComicBook/JusticeLeague storyline ''The Darkseid War'' and swimming through the Fire Pits of Apokalips then charging himself up with Kryptonite during ''ComicBook/SupermanSavageDawn''. That, combined with his DisneyDeath at the hands of the Kryptonian God Rao lead to the events of ''ComicBook/SupermanSuperLeague'', where Superman is now dying because of those changes.

[[folder:Fan Works]]
* ''The Beloved Helpless'': see the ''Manga/SoulEater'' entry above for [[TheCorruption Black Blood]] physics in this world. At the end of the fic, [[spoiler: Soul makes a deal with the Little Demon]] to use the Black Blood to save [[spoiler: Maka, who was mortally wounded by an insane Dr. Stein.]] It costs him [[spoiler: his soul, and when Maka finds him again, she figures out pretty quickly that the person she's talking to is his killer.]]
* Paul in ''Fanfic/WithStringsAttached'' actually starts out with his DeadlyUpgrade: he's made so strong that he can't even walk without soaring into the air and causing massive damage when he lands. He manages to shed much of the power by casting a small light spell and pumping energy into it until he explodes like a small nuke. Thereafter he is VERY wary of returning to high strength (which he finds he can do later) and practices constantly to get control of it when he does.
** In ''Fanfic/TheKeysStandAlone: The Soft World'', ten weeks of bad dreams and being afraid to touch his family mean that not only does Paul stridently resist going to high strength when he returns to C'hou, but that he now treats his lower level of strength as a Deadly Upgrade.
* ''Fanfic/CalvinAndHobbesTheSeries'': When Calvin [[SuperheroEpisode gains superpowers]], he also is prevented from regaining his energy, meaning that if he doesn't get it fixed (which will DePower him), he'll die of exhaustion. His powers also use a lot of his energy, which just speeds up the process [[spoiler: to the point where he dies near the end of the episode, which has to be undone by Hobbes time-traveling to the past and warning Past!Calvin to not do the thing that gave him superpoers.]]
* [[spoiler: [=ChaosGallantmon=]]] for Takato in the ''FanFic/TamersForeverSeries''
* [[WesternAnimation/DannyPhantom Danny]] develops a SuperMode in ''FanFic/FacingTheFutureSeries''. Unfortunately, while it does give him a massive power increase, the energy builds up too quickly and threatens to burn Danny's body out if he uses it too long.

[[folder:Folk Lore]]
* The [[http://www.monstropedia.org/index.php?title=Leanan_Sidhe Leanan Sidhe]] of Irish folklore does this. She grants inspiration to the artistic at the cost of sanity or even life.

* Creator/IsaacAsimov:
** ''Literature/FoundationAndEmpire'' had a scientist character whose ability to make intuitive logical leaps was overclocked in this way by an emotion-controlling telepath, which brought him to the brink of death.
** ''Literature/PebbleInTheSky'', which takes place in the same universe but long before the rise of the emotion-controlling telepath, has a technological means of permanently inducing a similar state. You think faster and clearer, and even develop telepathic powers... and then the increased wear and tear starts getting to your health, killing you within a matter of months.
* In Creator/AEVanVogt's ''{{Isher}}'' stories, the vibratory technology that enables the Weapon Shops can also be used by humans to grow into a several hundred foot tall giant that's practically invincible... but it will also cause you to age at an exponentially increased rate. This is, of course, no impediment whatsoever to secretly immortal [[TheChessmaster benevolent puppeteer of humanity]] Robert Hedrock.
* The ''Literature/YoungWizards'' book series features spells of this magnitude on occasion, which involve trading part or all of the caster's life to cast.
** There is also a "blank check" spell which will exact its price on you at a later date.
** Performing too many complex spells without rest can fry your brain.
** If you can get the Lone One to accept the Binding Oath, you can have temporary control over it, but there will be a backlash of negative consequences proportional to the degree of control, and you can only do this once.
* The ''Literature/SwordOfTruth'' series has "Wizard's Life Fire", an overclocked version of the already powerful Wizard's Fire that kills the user.
** Then again, this power is typically only used when all hope is lost and you're about to be killed already. Burn the enemy off the world as they take you out.
** There is also Con Dar, an overclocking of the Confessor's powers. It means "Blood Rage", and is only invoked on behalf of another. The main heroine survives it, but most, apparently, die after achieving their goal of revenge.
* In the world of ''Literature/TheWheelOfTime'', any magic users can do this if they draw on too much of the power. How much is too much varies from person to person, but if they use too much, potential consequences include losing the ability to channel (regarded as a FateWorseThanDeath because it's addictive), outright death, and {{Magic Nuke}}s. When Lews Therin did it, he created a volcano in the process.
* In ''Literature/TheCurseOfChalion'', the god known as The Bastard will occasionally grant a death miracle--the one who prays for someone else's death and the one who wronged him will always die. (The Bastard's death-demon can only enter or leave the world by the hole into heaven made by a death, so two deaths are required each time). A failed attempt is ''not'' fatal, but it is considered a crime of attempted murder--if the god didn't answer, the victim didn't deserve to die.
* Everywhere in ''Literature/TheDresdenFiles'', if only to prevent the eponymous character from getting GameBreaker levels of power. These include making a deal with the Leanansidhe ''twice'', and getting shafted both times [[spoiler:she winks out of existence without helping him the second time, and later discovers the first time she helped him, he didn't need it due to his [[ChosenOne special ability to wail ass on]] {{EldritchAbomination}}s all by himself.]] Then there is the fallen angel whose power he could call on, but too much and he risks losing control of his body. And Soulfire, which powers his spells [[spoiler:at the cost of his soul.]]
* In ''Literature/TheObsidianTrilogy'' by Mercedes Lackey and James Mallory, there are numerous ways to do this with magic, usually by trying to do something that carries a mageprice of death (or worse). Another, more specific example comes up in the third book, where it's revealed the city Mages had developed a ritual that would grant them effectively infinite energy for their spells, but the strain of which would kill them in seven years.
** In the latter case, [[spoiler: the more dangerous version was the ''original'' source of the High Mage's power. They figured out how to tap the mana of {{muggle}}s in order to keep their power without burning themselves out and over the generations forgot about the old ways.]]
* In David Weber's ''Literature/EmpireFromTheAshes'' series, the Earth defense forces give the planet itself one of these--a Core Tap (essentially a hyperspace funnel that produces ludicrous amounts of power but is highly unstable) is emplaced over Antarctica to power the planetary shield in advance of an invasion attempt (and as some idea of just how nasty one of those is, a microsecond hiccup in power would lead to the Core Tap exploding and flattening "fifty-three percent of the landmass of the continent, tsunamis, sea level rise and the direct deaths of 6.5 million people" with indirect deaths impossible to calculate. That's half of Antarctica, a continent bigger than the US, through three kilometers of ice.) The Imperials who worked with core taps before practically faint at the idea of putting one on a planet--they aren't even safe to use in atmosphere, and it's visible in operation as a two hundred kilometer torrent of lightning that is probably harmful to the Earth even when working perfectly.
* Lila Black from the Literature/QuantumGravity books' [[ShapeshifterWeapon original cybernetics]] have Battle Standard mode. This deactivates all of the safeties and limiters stopping them from ripping the user apart accidentally, goes to full power, puts the onboard AI in charge and doses the user to the point of insensibility with painkillers. It's also a bit buggy and doesn't always respond to the deactivation codes, but when you really, definitely, ABSOLUTELY HAVE to [[PersonOfMassDestruction kill everything within eyesight]] via MacrossMissileMassacre (watch the ammo expenditure), BeamSpam and StormOfBlades, and aren't particularly worried about [[HeroicSacrifice your own survival]], this should be your first port of call.
* In the ''Literature/{{Deathstalker}}'' books, the eponymous protagonist and all the male members of his family has the ability to "boost", a genetically engineered trait that lets them essentially overclock their bodies in combat. The comedown is at best uncomfortable and can be fatal if the boost is overused.
* In the ''Literature/LegendsOfDune'' trilogy, the Sorceresses of Rossak have MindOverMatter powers. However, they hardly ever use them. They spend most of the time training for the key moment when a Sorceress unleashes her power at full extent, frying any brain in the area... including her own. This is justified by the ongoing war between the [[FeudalFuture League of Nobles]] and the [[AIIsACrapshoot Synchronized Worlds]]. Specifically, a Sorceress's mind blast is the most effective weapon against the [[BrainInAJar Cymeks]], whose [[HumongousMecha mechanical bodies]] are resistant to most human weapons, since a psychic wave can't be shielded against. Norma Cenva subverts this. Her DeadlyUpgrade does indeed destroy her body the first time she uses it under Cymek torture. However, her mind is so powerful, she is able to rebuild her body molecule-by-molecule as a white-haired hottie (she was previously short and misshapen) by glimpsing at her female ancestors through the Other Memory.
* ''Literature/StarCraftTheDarkTemplarSaga'': After a protoss mystic named Zamara takes up residence in Jake Ramsey's brain, he's able to access both her expansive memories of protoss history and to some low-level psionic powers. [[spoiler:But the human brain isn't built to take on a second consciousness, and Zamara's presence leads to Jake developing a life-threatening brain tumor by the second book.]]

[[folder:Live Action TV]]
* ''Series/StargateSG1'' did this repeatedly:
** "Upgrades" had a set of gauntlets which accelerated human metabolism to give them superspeed and superstrength, but which suppressed the user's inhibitions, making them reckless. It also had a built-in time limit due to the user's immune system fighting off the virus it used to generate the effects. Of course, this has to happen at the most inconvenient time, in the middle of a mission...
** "The Fourth Horseman": An ascended ancient reverts to human form to help SG-1, but effectively overclocks his own brain to hold on to his godlike knowledge, eventually causing severe brain damage.
** "The Fifth Race" and "Lost City" both dealt with a device used to put information directly into one's brain; however, human brains are not advanced enough for it, and one's mind would eventually be totally overwritten by the knowledge transmitted.
** This happens to Daniel in "The Quest", though Merlin presumably controlled the information so it wouldn't kill him. However, as Mitchell pointed out, "you don't get fancy mind powers unless there has been major redecorating going on inside your skull!"
** The concept is lampshaded in the episode "200" where it is mentioned that to maintain the Status Quo, all that had to be done was to add a dangerous side-effect to any super-powers the characters may obtain.
** Ascension in general in the Stargate universe. By the time you get ascended enough to actually do something, you're not allowed to. Daniel barely got away just talking to folks during his ascension and eventually gave it up so he could go back and actually do something.
** Oma Desala taking on Anubis' ascended form in an eternal stalemate.
** Ditto for Ganos Lal doing the same to Adria in ''The Ark of Truth''.
* ''Series/StargateAtlantis'':
** Lt. Ford is addicted to a Wraith enzyme that gives the user superior strength and durability, but causes a kind of madness. Ford's men eventually die in Wraith custody from withdrawal. [=McKay=] takes an obscenely-high amount of the enzyme, becoming a small colossus; he overpowers his guards and races back to the stargate, collapsing on the Atlantis control room floor and has to ride out the withdrawal in the infirmary.
** Also, Dr. [=McKay=] gets zapped by an Ascension Machine (I defy anyone to come up with a less ridiculous description) and gets a few superpowers. But of course (in a hilarious scene) he finds out he has to ascend or die.
* ''Series/DoctorWho'':
** In the episode "The Parting of the Ways", Rose absorbs the Time Vortex, gaining [[AGodAmI godlike powers]] which would have killed her had the Doctor not sacrificed himself instead.
** In the series 4 finale [[spoiler: Donna Noble gained the mental power of a Time Lord, which allowed her to be a critical aid in defeating Davros and the Daleks. However, once everything was done it began to [[MySkullRunnethOver overload her brain]], forcing The Doctor to [[VictoryGuidedAmnesia erase her memory to save her]]]].
* ''Series/{{Angel}}'':
** The deadlier sort of HilarityEnsues when Lorne has his sleep removed for a party. Albeit, unlike most other examples of this trope, this was deadly to everyone else, rather than to Lorne himself...
** Illyria inverts it into a deadly *downgrade* sort of thing when she, a powerful Old One, revives in a human body-Fred's body can't take Illyria's power for long, and the gang has to drain some of it before she explodes and takes the whole world with her.
** The MonsterOfTheWeek Angel faces in the Season 3 opener "Heartthrob" was James, a former vampire protege of Angelus who had [[SoulJar removed his own heart]] to make himself unkillable. He sought to use his invincibility to kill Angel as revenge for his killing James' girlfriend, but the powers only lasted for six hours before he spontaneously turned to dust.
** And Cordelia, who got the visions from Doyle, but they weren't meant for humans, and she had to let herself be made part demon before the visions either drove her insane or [[BodyHorror blew out her skull.]]
* Series/BuffyTheVampireSlayer [[spoiler:[[PsychoLesbian Dark Willow]]]], anyone?
** And Buffy herself, when she became telepathic. Eventually, she got overwhelmed and went into a HeroicBSOD until the cure was given to her.
* ''Series/StarTrekDeepSpaceNine'': An alien woman seduces Jake Sisko, and heightens his creativity so that she can absorb the resulting energy, causing him to write compulsively to the point of collapse and beyond. Needless to say, the heroes discover what is happening just in time to save his life.
* In the 2000 ''Series/TheInvisibleMan'' TV series, Darien Fawkes can make himself invisible by the means of "Quicksilver", a substance secreted by an artificial gland implanted in his brain -- but the gland also secretes toxins that will drive him mad and kill him, if not neutralized with a shot of "counteragent."
* ''Series/{{Chuck}}'' does this with anyone not named Bartowski, as the Intersect -- a program that downloads all the US Government's secrets into a person's brain -- burns out your brain, fries your memory, and at best makes you an emotionless machine, or at worst [[DrunkOnTheDarkSide turns you evil]].
* Most of the more recent ''Franchise/KamenRider'' series have used this trope as a plot point.
** In ''Series/KamenRiderKuuga'', the main character has an "ultimate form" that he can assume, at the risk of [[spoiler:becoming evil]].
** In ''Series/KamenRiderAgito'', one of the riders (Gills) [[spoiler:suffers cellular decay from continued transformations]].
*** The first version of the G3-X Armour would [[spoiler:cause several physical strain on a user that wasn't completely submissive to its "perfect" AI system]]. The G4 Armour, while being the most powerful version, would eventually [[spoiler:kill the user from overexertion]].
** In ''[[Series/KamenRiderFaiz Kamen Rider 555]]'', the Orphenochs seem to be the embodiment of DeadlyUpgrade: they are dead humans who either become Orphenochs after suffering some accidental death, or are "sired" by other Orphenochs. The process requires the human to die either way. Not only that, but they [[spoiler:are subject to physical degeneration over time]]. The way to prevent this decay, however, [[spoiler:destroys any remaining vestige of their prior humanity]].
*** The Kaixa Gear [[spoiler:consumes Orphenoch DNA as fuel, consuming so much]] that most users die after a single use. The Faiz Gear works much the same way, but has a warning system that rejects users it would kill. The Delta Gear works for anyone, but carries a risk that [[spoiler:the user will become addicted to the power]].
** In ''Series/KamenRiderBlade'', the title character's SuperMode King Form works by [[spoiler:fusing his body with the power of the 13 Category Spade [[MonsterOfTheWeek Undead]]]]. However, [[spoiler:since this is a fusion on the DNA level, it starts gradually turning Blade into an Undead himseld]]. [[spoiler:In the SeriesFinale he deliberately over-uses King Form with the express intent of becoming an Undead, as part of his [[TakeAThirdOption Taking a Third Option]] to TheEndOfTheWorldAsWeKnowIt.]]
** In ''Series/KamenRiderHibiki'', the Armed Saber can grant a massive power boost to an Oni Rider, but only if they're properly prepared for it; otherwise they lose the ability to transform. [[spoiler:However, all four of the Oni to whom this happens end up regaining their transformations with further training, and Hibiki (one of the victims) goes on to gain a full-fledged SuperMode out of the Armed Saber.]]
** In ''Series/KamenRiderKabuto'', the Big Bad [[spoiler:forcibly transforms himself into a monster in a final attempt to destroy the hero]]. The SuperPrototype Hopper Zecters seem to come with a requirement of [[WithGreatPowerComesGreatInsanity insanity]].
** In ''[[Series/KamenRiderDenO Kamen Rider Den-O]]'', Zeronos uses cards that [[spoiler:consume the memories that others have of his older self]] to transform. Later, his PaletteSwap upgrade Zero Form [[spoiler:changes things so that the memories consumed are of his present self]].
** In ''Series/KamenRiderKiva'', the prototype IXA system puts incredible strain on its user's body, and can only be used for a short period of time before apparently overheating. [[spoiler:The heroes actually exploit this by tricking a powerful enemy into using the IXA Knuckle, which weakens him enough that they almost kill him before he manages to retreat]].
*** The power of Dark Kiva takes an even more savage toll on its user if they are an ordinary human rather than a Fangire.
** The [=FangJoker=] form of ''Series/KamenRiderDouble'' was alleged to be this, driving Philip violently insane, but it proved to be a psychological block rather than a trait inherent to the form and was thus overcome.
** ''Series/KamenRiderOOO'' can use three Medals of the same kind to achieve a Combo, gaining a SetBonus superpower at the cost of considerable exertion. Ankh warns that Combos will be addictive and otherwise deleterious to the user's mindset, which is true based on his experience, but proves to be inaccurate: OOO feeds off and amplifies the user's greed, and Eiji is utterly lacking in worldly desires, making him largely immune to the dangers of the belt's power. However, the final upgrade he receives, [=PuToTyra=] Combo, represents [[ExactWords the desire for nothing]], and the same mindset that makes Eiji immune to corruption by the other Combos makes him a puppet of this one's influence. Even when he overcomes the short-term dominance the purple Medals exhibit over him, they continue to steadily corrupt his mind and body so that he'll become a monstrous OmnicidalManiac sooner or later: he has no means of stopping it, so it's only a matter of how long he can resist. So deadly is this upgrade that in the finale Eiji destroys it to save himself and the world from it, and in all future canonical material [=TaJaDor=] Combo becomes his new final form, with [=PuToTyra=] only ever seeing use again in non-canonical films where RuleOfCool is in full effect.
** In ''Series/KamenRiderGaim'', three of the main characters undergo such transformations. Gaim's [[SuperMode Kiwami Arms]] slowly transforms him into a [[MonsterLord Over Lord]] with each usage, taking away his desire for any food but the fruit of the Helheim Forest. Baron's EmergencyTransformation into an Over Lord grants him a monstrous form with vastly increased power, but the infected wound he used to access the form continues to slowly kill him. Ryugen's version, meanwhile, comes across as more of a parody: the Yomotsu Heguri Lockseed he's given by the local MadScientist will supposedly use his life force to give him immense power to rival Kiwami Arms. In practice, [[ClippedWingAngel the upgrade inflicts so much pain on the user that they're left writhing in agony and unable to do anything useful with that power]], so much so that Kouta could have beaten him without even transforming if he'd wanted to.
** ''Series/KamenRiderDrive'' shares the Type Deadheat upgrade with his secondary Rider Mach, which both use to achieve ExplosiveOverclocking at the cost of eventually going berserk, a drawback Mach eventually overcomes. Type Formula is even more deadly, as its SuperSpeed is too much for the user's body and using its Rider Kick might kill them. Unusually for such threats, this actually ''did'' happen the one time he used it, but a GroundhogDayLoop was in effect at the time and he got better.
** Emu's first use of the Mighty Brothers XX Gashat in ''Series/KamenRiderExAid'' causes him to begin suffering blackout-inducing headaches that reduce in intensity but grow in frequency with time, even when not using the Gashat. He eventually appears to overcome this drawback via CharacterDevelopment.
** The Sclash Driver in ''Series/KamenRiderBuild'' is said to be an improvement to the original Build Driver, but every usage makes the user more aggressive and violent than the last. For a while Sento does his best to keep Banjou from using it for this reason, but he manages to conquer it via force of will.
*** '''Build''' also has the Hazard Trigger, which powers up Build's normal forms to a ludicrous extent. However, prolonged usage causes his mind to shut down from over-stimulation, turning him into a bloodthirsty berserker who attacks friend and foe alike with intent to kill. [[spoiler:This causes Sento to kill another human being, triggering a HeroicBSOD. He manages to overcome the problem by inventing the [=FullFull RabbitTank=] Bottle, which manages to diffuse the Hazard Trigger's power enough that it's still useful but no longer a threat to himself or others.]]
** However, before them all was ''Series/KamenRiderStronger,'' the first Rider to have a SuperMode, or any form-changing at all. (If we don't count [[Series/KamenRiderV3 Riderman's]] different arm attachments, anyway.) If he uses Charge Up, he's got to burn through the extra energy in sixty seconds, [[ExplosiveOverclocking or else]].
* In ''Series/MahouSentaiMagiranger'', the Ozu children eventually gain the upgrade Legend Form. Unfortunately, using this form even a little will cause them to [[spoiler: turn into Heavenly Saints themselves, thus losing all memory of their human life]]. The only way to avoid this is for [[spoiler: Magi Shine to use a magical limiter on them which lessens the overall power they gain in this form, but ultimately keeps them human]].
* In an episode of ''Series/RedDwarf'', Kryten comes up with a plan to restore Holly's computer-senility-ravaged IQ to its original level at the cost of operational runtime. Due to a miscalculation, her IQ is actually ''[[YouFailTheIQTest doubled]]''...but she ends up with just under four minutes to live.
* ''Series/{{Farscape}}'':
** In ''The Peacekeeper Wars'', John goes rather comatose after activating (and deactivating) the wormhole weapon, as the agreed-upon removal process of the implanted wormhole knowledge had the possibility of frying his brain. Doesn't mean he can't create his own version of the tech in time though.
** In an first-season episode, a weapon known as the [[ArmCannon Gauntlet]] is introduced: it's capable of firing energy blasts, creating energy shields, and it even injects the user with a powerful stimulant which boosts their strength, speed and stamina- though it does tend to give new users [[WithGreatPowerComesGreatInsanity delusions of grandeur]]. However, a season later, [[GondorCallsForAid Crichton is trying to get help from characters he ran into during the first season]], and naturally goes looking for the Tavlek mercenaries who use the gauntlet; unfortunately, the only one he can find has found religion and refuses to help, so Crichton just finds the gauntlet and decides to wear it himself... only to recieve a curt warning that the stimulant dosage has been boosted- enough to kill him in about three hours.
* In ''Series/SuperRobotRedBaron'', the titular giant robot has "Baron Full Power", a last-resort attack mode that uses [[DepartmentOfRedundancyDepartment all of its power reserves]]. However, if it's used for longer than one minute, Red Baron will [[ExplosiveOverclocking explode(!)]]. [[spoiler:Luckily, that possible outcome is averted, since it [[NewPowersAsThePlotDemands only gets used twice]]]].
* The Karakuri Giant Senpuujin of ''Series/NinpuuSentaiHurricaneger'' has a Super Mode called Hurrier Mode, which sheds its armor and allows it to be faster and agile for sixty seconds. If it doesn't revert back within that time, it'll suffer internal damage.
* Werewolf George in ''Series/{{Being Human|UK}}'' finds a way to trick himself into partially turning into a werewolf without the moon in order to have the strength to save his daughter from being killed by vampires. Unfortunately, the Werewolf transformation is compared to dying and being reborn and partial transformation leaves out the last part.
* ''Series/{{Charmed}}'': Happens when people who aren't meant to be Empaths take (or are given) a legit one's power anyway. However, Prue really turns it UpToEleven: powers in Charmed are fueled by emotion, and the more emotional you become the stronger your powers become. So, when Prue gets the empathy power she feels more emotions (specifically, those closest to her), so her empathy power becomes stronger. Its area of effect therefore increases, so she feels more (further off) emotions, so her empathy power becomes stronger again, so her area of effect increases again--positive feedback continues ad infinitum. Unfortunately, on top of the fact that these power boosts occur quicker than she has time to adjust to them (making them exponentially unstable), she still has her original powers, which logically "piggy-back" on the gains made by the empathy feedback loop. Given that one of them is telekinesis, the result is ... [[SuperPowerMeltdown interesting]].

[[folder:Live Action Film]]
* In 90's ''Franchise/{{Godzilla}}'' films, the King of Monsters can fire a much stronger version of his blue atomic beam that is red and has lightning spiral around it if he absorbs enough energy. The down side is if he absorbs too much power he will turn into a meltdown mode that will cause a SuperPowerMeltdown that can burn up the atmosphere and kill all life. In ''Film/GodzillaVsDestoroyah'', he does end up going into meltdown mode. It's only by his son Godzilla Junior does the Earth survive: [[spoiler: when Burning Godzilla finally has a total meltdown, Junior is forced to abosrb the excess radiation, maturing into a new Godzilla.]]
* ''Film/{{Lucy}}'': After accidentally getting an overdose of a synthetic hormone, Lucy finds herself rapidly gaining control over her mind and body, the minds and bodies of others, and the physical world around her. She quickly realises that this will kill her, and nearly disintegrates at one point, only stopping it with another dose of the drug.

[[folder:Tabletop Games]]
* One of the mutant powers in ''TabletopGame/{{Paranoia}}'' is Adrenaline Control, giving the character superhuman strength by having his body working at maximum capacity. This is never a good thing: "he's Superman for a minute, but...pays for it."
* A supplement for the ''TabletopGame/MutantsAndMasterminds'' system includes a drawback ([[GameBreaker though how much of a drawback it really is is contested]]) called Holding Back. When triggered, the character in question gains a huge power boost, but side effects range from attracting attention from powerful enemies to going berserk on your allies to becoming comatose afterward.
* The ''Complete Mage'' supplement for the [[TabletopGame/DungeonsAndDragons 3.5th Edition of D&D]] features the spell [[ExactlyWhatItSaysOnTheTin "Transcend Mortality"]] for the [[ElementalPowers Wu Jen]]. It gives [[NighInvulnerability DR 30/epic]], [[PowerNullifier SR 21+CL]], [[ElementalRockPaperScissors resistance to all five energy types]], [[StandardStatusEffects immunity to abilitiy damage/drain/disease/poison/death effects]], and [[SuperNotDrowningSkills negates your need to breathe]]. The catch? The spell lasts for roughly 2 minutes (depending on the mage's level), after which [[DisintegratorRay you immediately die and turn to dust]]. Said death cannot be prevented by ''any'' means.
** As with all things D&D, this can be made into a GameBreaker. The Spellguard of Silverymoon learns to cast spells on nearby others that normally only work on themselves. And Transcend Mortality can be dismissed by the caster at any time.
** Also, while DeathIsCheap by the time you can use it, only four very, ''very'' powerful spells can bring back someone who has been turned into dust. Namely:''Wish'', ''True Resurrection'', ''Contingent Resurrection'' (which is an Epic level spell), and ''Miracle''.(although you can create more epic spells to resurrect someone from such a state)
** AD&D incarnation of Leanan Sidhe (see above) -- a vampiric spirit who charms bards, inspiring, and boosting their abilities, but gradually draining hit points (permanently).
* ''{{TabletopGame/Rifts}}'' has two classes that fall under this trope.
** The first are Juicers. Chemicals (and nanomachines) are constantly pumped into a human to turn them into a superhuman - but at the cost of burning out and dying after five years.
** The second are Crazies, which use brain implants to coax the mind into pushing the body past it's normal limits. The result is a character who is significantly stronger, faster, and more agile than a normal human, but the implants cause a lot of strain on the mind, eventually leading to a long list of insanities.
* TabletopGame/ChangelingTheDreaming used Leanan Sidhe to create a whole house of Sidhe who did just that - and a game mechanic for all fae to do the same.
* Eversor Assassins in TabletopGame/{{Warhammer 40000}}. These drug-crazed killing monsters are called the Latin word for 'Destroyer' for a reason, enemies (or walls) don't last long when they are around. Eventually all of the genetic alterations, combat drugs, and bionics with which they are equipped overwhelm their hyperactive immune system and they overheat rather explosively. The only thing that keeps them alive between missions is that they are kept in cryogenic stasis.
** While on smaller scale, most of Psykers too. Every single use of psychic power risks to attract Predators of Warp. Better make it count.
** The Tau Riptide Battlesuit has an experimental Nova Reactor, which enebles it to "super charge" its weapons, shields or jetpack, at the cost of the radiation overload potentially killing the pilot.
* ''TabletopGame/{{Exalted}}'' has a martial art technique known as Birth of the Perfected Ego Juggernaut. Anyone (ally or enemy) struck by it gains an enormous power boost, allowing them to effortlessly succeed at nearly anything...for about ten minutes. Each minute after the effect activates, the power drops a bit, until by the tenth it's gone entirely. The catch is, at no point does the subject of the attack notice the decline. To themselves, they remain an awe-inspiring, completely unstoppable force of nature. The madness creates elaborate excuses for failures and is permanent (baring healing magic, which does nothing to stop any feeling of depression in someone no longer effortlessly flawless).
* In ''TabletopGame/TheDarkEye'', druids have a skill to transform all their life points, endurance points and several attributes into magic ability and cast spells without restriction for an hour. Once started, the process cannot be stopped, and the caster ends as [[DeaderThanDead a pile of ashes]].

[[folder:Video Games]]
* The eponymous mark in ''VideoGame/MarkOfTheNinja'' is made of a plant toxin that, when applied to the skin, gives a variety of sense-enhancing powers to anyone with the tattoo but eventually drives them to murderous insanity. As such, people who accept the mark take an oath to commit suicide once their mission is over.
* In ''VideoGame/BaldursGate2'', the PC is granted the ability to assume the form of the Slayer, a manifestation of his dead father Bhaal, the God of Murder. Not only does maintaining the transformation kill you, using it is an inherently evil act that lowers your reputation, and may cause you to turn on party members.
* ''VideoGame/DungeonFighterOnline'':
** Berserkers get the Frenzy skill, which more or less makes them BloodyMurder Personified (blood weapons, Blood boost), but drains health over time. Though use of HP regeneration [[BribingYourWayToVictory Avatar items]] can slow the process.
** The Berserker skill, Thirst, qualifies as well. At a cost of 12 percent of the berserker's max HP, bleeding damage is significantly increased, certain skills do more damage, and the berserker can absorb more HP from his slain enemies. This, combined with Frenzy, makes the berserker's HP unstable as it's constantly shifting upward or downward.
* ''VideoGame/FrontMission'' has a fair bit of these as shown in the video games and other media.
** The Bioneural Device is a unique interfacing device that lets pilots control their machines with human-like precision, often allowing them to exceed said machine's limitations in performance. However, pilots must undergo special augmentation surgeries which don't always quite turn out for the best. Puppet Soldier users have greater control over their machine's motions, but their minds can be taken over and actions remotely controlled by a "puppet master". Doll Eye users have 360 degree vision and can control nearby electronic systems to some extent, but are subject to blindness and extreme eye pain if they are hit with flash bang grenades. S-Type users can control their machines as if it were their own bodies and can do incredible feats on the battlefield because of it, but they are physically affected by EMP attacks, their organ sensitivity is so high that even minor damage can be fatal, and they can suffer from massive memory loss. Puppet Soldier shows up in ''2089'' and ''2089-II''. Doll Eye appears in ''2089-II'' and the ''Dog Life & Dog Style'' manga. Finally, S-Type can be seen in ''2089'', ''2089-II'', ''1st'', ''Online'', ''5'', and ''Dog Life & Dog Style''.
** While it isn't exactly like the other Bioneural Devices, the B-Type also counts in a way. The B-Type is a device which is powered by a human brain and when put inside a machine, allows for autonomous control of it. Machines can attack targets or evade enemy fire without needing input from its pilot. The downside? B-Type devices are very unstable and have led to the deaths of pilots using machines with it, [[spoiler: such as Laurent Connely when his B-Type-powered wanzer stopped moving and he was shot to death by nearby OCU units.]] Appears in ''1st'' and ''Online''.
** The Imaginary Numbers in ''3'' also count. The Imaginary Numbers are a group of genetically engineered humans with above-average intellect and exceptional abilities in combat, such as their reaction time and tactical knowledge. The Imaginary Numbers, while deemed superior to their predecessor the Real Numbers, were far less stable mentally and thus vulnerable to becoming insanity under certain conditions.
* ''[[VideoGame/GuardianHeroes Advance Guardian Heroes]]'' combines this trope with DealWithTheDevil: if you run out of HP, you're given the option of being granted an even more powerful body for a limited time. Accept, and you will be given an invincible body for six minutes. Once the time limit expires, though, your soul will be taken, and you will receive a GameOver, with your progress being set back to before you accepted the offer.
* ''VideoGame/MassEffect2'' shows this as an ability of the Collectors, a curious race who have more implants than internal organs per member. As [[BigBad Harbinger]] [[MoreThanMindControl takes direct control of a mook]], these implants go into overdrive, and the individual Collector gains a massive damage buff, [[TheForce biotic abilities]], and a [[VolcanicVeins evil-look]][[GlowingEyesOfDoom ing glow.]] However, as they take more and more damage, their implants are forced to increase in power, until they can take no more, and the Collector's body is disintegrated. [[WeHaveReserves Not like Harbinger cares, though.]]
* In ''VideoGame/CastlevaniaPortraitOfRuin'', it is revealed that the Vampire Killer whip drains the life force of any non-Belmont who uses its true power. Jonathan Morris is warned against relying on it too much. Luckily for him, though, it takes longer than covered in one game to kill you... [[spoiler:but his father used it too often, which ultimately killed him.]]
** Also, in ''[[VideoGame/CastlevaniaOrderOfEcclesia Order of Ecclesia]]'', you can get an item called the Death Ring. It boosts all your stats by a considerable amount...at the cost of you effectively becoming a OneHitPointWonder.
*** There are also the Dominus Glyphs. Using one deals tremendous damage, and at the same time takes off a sixth of your HP.
*** Not to metion using the Dominus Union. It will kill all enemies on-screen [[spoiler:at the expense of consuming your soul and thus killing you.]]This later becomes [[spoiler:an important plot point.]]
* The dragon transformation in ''VideoGame/BreathOfFireDragonQuarter'' results in rapid accumulation of points on the D-Counter, which constantly increases at a much slower rate, cannot be lowered by any means, and results in a NonstandardGameOver when it hits 100%, strongly discouraging you from using it at all.
** Similar deal in ''VideoGame/BreathOfFireIII'' with the Kaiser dragon form. It's Ryu's most powerful dragon form, but the first version you get you can't control Ryu when he uses it. You can however, get a controllable version.
* ''VideoGame/EarthBound'' has the party [[spoiler:become robots in order to time travel, because time travel does not work on organic matter. No guarantee exists that the characters' souls will find their way back from the robots afterward, though naturally they do.]]
* In ''VideoGame/FinalFantasyIVTheAfterYears'', Ceodore learns an ability called Awaken. When he uses the ability, his stats increase dramatically, but a few turns later, he drops into single-digit hit points, meaning one hit from anything and he dies. This is definitely deadly if a battle is still going on.
* In the ''Heaven's Feel'' route of the ''VisualNovel/FateStayNight'' {{V|isualNovel}}N, [[spoiler:Shirou gets Archer's arm transplanted onto him after his own is lost and Archer is dealt a fatal wound]]. It is wrapped in a cloth that seals its power, but even if left like this, it would kill him from power overload within ten years unless he [[spoiler:cut it off or became a good enough mage to seal it himself]]. Just ''loosening'' the cloth causes significant memory loss; taking it off completely is a guaranteed death sentence, with rapid destruction of mind and body on top of that with every use. [[spoiler:He still manages to overcome Black Berserker, Saber Alter, Kotomine, and (in the "Normal End") the corrupted Grail before his mind dies.]]
* In ''Franchise/DotHack'', Kite has Data Drain, which weakens enemies to the point where they can be taken out with a single hit. But using it can result in level and stat reductions or an instant game over. He gets an upgrade that allows him to use it on multiple targets and yet another that increases the chance of getting a rare item, but both increase the likelihood of negative effects occuring.
* The Mercenary's of ''VideoGame/TeamFortress2'' have all underwent an entire heart transplant that replaced their normal hearts with that of the "Mega Baboon" and possibly even the "Loch Ness Hamster" to be able to be used for an ÜberCharge. However, as [[MadScientist The Medic]] has shown, normal hearts tend to explode when exposed to the beam that grants the charge, and he prefers to perform the operation while his patients are still awake. Making the threat of bleeding out or loosing vital organs to the mad man seem very possible despite the healing devices he has seat up.
* In ''VideoGame/{{Haze}}'' you have access to a super-drug called ''Nectar'' which gives you enhanced speed, accuracy, and grenade range, but overdosing could result in losing control of your character or even death.
* In ''VideoGame/{{Crimsonland}}'' you can activate the ''Death Clock'' perk which gives you 30-second invincibility... After which you die.
* A central point of ''VideoGame/MetroidPrime3Corruption''. Samus gets a powerful "Phazon Enhancement Device" added to her suit that allows her to transform into a hyperactive killing machine, but over-use of it will cause her to become 'corrupted' and [[NonstandardGameOver end the game.]]
** And even if you don't overuse it, it'll probably kill you anyway - witness the PED-equipped Marine with the suspiciously shaky hands in the Preview Channel video, to say nothing of [[spoiler:the other three hunters, who apparently go over to the Dark Side right out of the gate, and AU 242's warning to Samus on Bryyo:]]
-->[[spoiler:"We have discovered that the unique Phazon in your body, once activated, will eventually overreact, resulting in terminal corruption. In providing you with the PED, we have inadvertently placed you in grave danger. (pause) We are sorry."]]
*** And in a moment of FridgeBrilliance, using the PED also explains why the SpacePirates' experiments with Phazon frequently caused UnstoppableRage: Firing indiscriminately is the easiest way to get rid of excess Phazon, preventing an overdose.
* In ''VideoGame/LuminousArc3'' [[spoiler:Refi]] receives one that greatly powers him up, at the expense of losing his humanity every time he uses it, starting with his senses. Surprisingly enough it is strongly impled that he [[spoiler:has not regained the senses he lost by the end of the game]]
** Debatable as some ending implied that he has.
* Used in ''VideoGame/KingdomHeartsII'' with Anti-Form. Engaging a Drive form (other than Final Form) has a chance of instead turning into Sora into something akin to TheHeartless (suggested to be his connection to [[spoiler:when he briefly changed into one in the first game]]). Anti-Form is completely unable to gain experience, and it's completely unable to recover health. Slightly related to both, it's also the only form that Sora can't cancel partway through. It's not bad if you're just starting against a boss, and at full health. But if either recovery or experience points are in the coming, you will be affected by the downsides.
** And naturally, it is much more likely to pop up in battles with Organization XIII members, many of whom are the bosses you [[ThatOneBoss most need healing and damage resistance for]].
* In ''VideoGame/PrinceOfPersiaWarriorWithin'' the Prince at one stage [[spoiler:puts on the 'Mask of the Wraith', which sends him back in time and transforms him into a monstrous wraith. In this form his health slowly drains, stopping at 25% of base health (enough to take a single hit without dying, and then only certain ones) but his sand tanks refill on their own at such a fast rate that he effectively has unlimited sand.]] Under the circumstances, you need it.
* In ''VideoGame/PrinceOfPersiaTheTwoThrones'' at certain points, the Prince transforms into the Dark Prince, who is faster and stronger, but cannot use his left hand for grappling or picking up weapons, instead he has a spiked chain-whip. In addition, he slowly loses life to the darkness (unlike the above, this will be fatal eventually), which can be replenished by absorbing Sands of Time. He reverts back to the original Prince if he touches water.
* In ''VideoGame/PrinceOfPersia2: The Shadow and the Flame'', transforming into the Shadow shortens your life meter by many potions, and using the Flame [[CastFromHP costs further health]]. Both are necessary to defeat the FinalBoss.
* One mission in ''VideoGame/DevilMayCry 3'' has Dante acquire a key needed to progress to the next area. Said key drains the soul of the bearer, and he can't let it go until he reaches the area it's used. Of course, sticking around too long without health refills will eventually kill him. To give Dante a fighting chance, the key also allows him to be in [[SuperMode Devil Trigger form]] permanently.
** This is [[CallBack an echo]] of a mission in the original ''VideoGame/DevilMayCry'', which carried all the same consequences for waiting around along with the same perpetual Devil Trigger benefit.
* Rampage Mode in the ''VideoGame/{{Oneechanbara}}'' series, a product of the Baneful Blood carried by most of the playable characters. Their offensive abilities are greatly increased, at the cost of taking double damage and constant health drain. There's also a Double Rampage Mode which is even more powerful and even more deadly.
* ''VideoGame/ValkyrieProfileCovenantOfThePlume'' has the titular Destiny Plume - when used on an ally, it multiplies their base stats by 10, makes them immune to status aliments and elemental damage and uses an extremely powerful character-specific ability TheHero learns permanently after the battle, but it [[KilledOffForReal costs them their life]] at the end of the battle. It could almost count as a HeroicSacrifice, except the choice is never theirs to make.
* At the end of ''VideoGame/IndianaJonesAndTheFateOfAtlantis''. [[spoiler:You discover an ancient Atlantean machine that transforms men into gods, and the Nazis want to reward Dr. Jones for the find by letting him be the first to use it and ascend to godhood. But this will inevitably result in BodyHorror.]]
* ''VideoGame/AgeOfWonders: Shadow Magic'' has [[http://aow2.heavengames.com/aowsm/gameinfo/magicspells/life.shtml#martyr Martyr]] enchantment: it doubles one unit's HP, but this unit dies once the battle ends.
* Rugal Bernstein of ''VideoGame/TheKingOfFighters'' acquired some of the Orochi power after '94, becoming Omega Rugal. The problem is that those without the Orochi bloodline have no way of controlling it. After his defeat in '95, the power overloads and reduces him to his component atoms.
* ''VideoGame/MissionCritical'' features the [[UnusualUserInterface Hype/Telecon System]], which allows the player to control the ship's combat drones with his mind - at the same speed as computer guidance systems. Unfortunately, the nanotech injection required causes certain death within a few days.
* In ''VisualNovel/{{Tsukihime}}'' even before the story starts, Shiki had the Mystic Eyes of Death Perception activate, greatly supplementing his killing power. Obviously. Of course, it burns his brain out and he'll die in ten years or so but... Also when he overtaxes even ''that'' in order to see [[spoiler:Satsuki's polluted blood in his veins, open his brain up to be able to comprehend the death of things that aren't even alive, and worst of all, use his eyes as X ray eyes ''while'' looking for poison to kill in Kohaku's blood. The last one sends him temporarily blind as well as surely cutting his life back a few more years.]]
* If the Mimigas in ''VideoGame/CaveStory'' consume the red flowers, they transform into giant, hulking, quite literal {{Killer Rabbit}}s. Unfortunately, this transformation cannot be reversed, it drives them insane with bloodlust, and it kills them after a short time. The Mimigas did once eat the flowers deliberately in order to drive off a great threat, knowing full well that those who did so were sacrificing themselves regardless of whether they won or not.
* Ragna the Bloodedge from ''VideoGame/BlazBlue'' has his Azure Grimoire(or Blazblue to go with the title drop). His right arm gets chopped off in his backstory and is replaced with the remains of an EldritchAbomination. Said arm makes him a OneManArmy strong enough to be considered to be the most wanted man in the world, however using it causes the arm to assimilate and turn him into said EldritchAbomination. Naturally Ragna is extremely reluctant to use it unless he's pushed far enough. In gameplay, this translates to his "Blood Kain" LimitBreak, which augments his damage output and combo potential but drains his health bar with each passing second.
* ''VideoGame/CommandAndConquerTiberiumWars: Kane's Wrath'' has something like this the Steel Talon subfaction has two of these. The first railgun accelerator support power. It increases rate of fire of a unit that a railgun, but they take damage when it's first cast them. Not too big of an issue because the Steel Talons can easily repair their vehicles. They second is the adaptive armor support power. It makes a vehicle more durable grants it immunity to EMP weapons (very good for an epic unit because EMP weapons are of the main counters to them), but lowers their rate of fire. Can be remedied with the railgun accelerator if the unit uses railguns. Common strategy is to use both on the unit an enemy concentrates fire on at the start of battle.
* ''VideoGame/BattleClash'' and ''Metal Combat: Falcon's Revenge'' have a power-up called the V-System, which increases your offensive ability and always keeps your opponent centered within your sights. In order to power this, however, your mech's energy gauge is continuously drained until you reach critical.
* It's not quite ''deadly'', but the Mega Mushroom in ''VideoGame/NewSuperMarioBros'' has the side effect of returning you to Super Mario form when its period of invincible AttackOfThe50FootWhatever wears off. Thus, if you picked it up as Fire or Blue Shell Mario, it has the net effect of stripping Mario of one of his maximum three HitPoints.
* In the web-only game VideoGame/{{KOLM}}, the final upgrade you receive [[spoiler:causes a nuclear meltdown that destroys your entire home, the only place you ever see in-game. You, however, can survive]].
* In ''VideoGame/StreetFighterXTekken'', this is how Pandora works in gameplay: by sacrificing the character that you are currently using, your standby character gets a massive boost in attack power. If you can't defeat your opponent within ten seconds of activating Pandora, however, you lose automatically.
* In ''VideoGame/{{BioShock|1}}'', the first Plasmid power you receive causes Jack to temporarily go mad and black out. Habitual plasmid use [[InformedFlaw supposedly]] causes disfigurement and eventually permanent insanity (hence all the insane splicer enemies you fight), but [[GameplayAndStorySegregation that never seems to happen to the player]] no matter how much you splice, [[spoiler: but that may be because of the many changes Fontaine and his allies made to you when you were created.]]
* In one mission of ''VideoGame/AssassinsCreedBrotherhood'' you get to use [[spoiler:the Apple of Eden. Any one within a certain distance goes crazy and starts fighting each other. Anyone in an even closer distance automatically dies. Every time it is used time slows down and your health gradually goes down. And you can't use any of your other weapons.]]
** ''Revelation'' averts this completely. We find out Altair had the same ability but none of the drawbacks. Apparently he was a major badass for a reason.
* ''VideoGame/{{Persona 3}}'' has this in spades. First, many Personas learn physical attack moves, but using them drains up to a fifth of the character's HP. [[spoiler: Also, Jin, Takaya, and Chidori were artificially given Personas, which will kill them if not controlled by drugs... [[SadisticChoice and the drugs' side effects include a vastly shortened lifespan.]]]]
** [[spoiler: Not only that, the last move that the Main Character uses to seal away the final boss [[HeroicSacrifice costs him or her their life.]]]]
* ''Wolverine'' for the UsefulNotes/NintendoEntertainmentSystem makes WolverineClaws work this way. Once Wolverine unsheaths his claws, they replace the icon of his face and make his attacks hit harder while draining his life bar.
* In ''[[VideoGame/AsurasWrath Asura's Wrath]]'', the main character at one point enters his [[spoiler: Berserker Form]], an incredibly powerful form capable of [[spoiler: shooting down an entire armada]], but at a cost - after Asura is struck directly by [[WaveMotionGun the Brahmastra]], he enters his [[spoiler: Wrath Form]]. This scorches his body black with the fires of his own rage and it's stated that Asura's attacks do more damage to himself than his opponent when in this state.
* ''VideoGame/KillerInstinct'' has this mixed with GhostInTheMachine and UnwillingRoboticisation on Eagle. [[spoiler:After ratting [=UltraTech=] out upon winning, the company turns him into a machine, Fulgore. Unfortunately, Eagle inverts the CyberneticsEatYourSoul trope by the 2013 remake, resulting in this.]]
* ''VideoGame/SuikodenV'' introduces Raging Nostrum, a very dangerous drug developed by assassin network Nether Gate. Those who ingest the drug go into a violent rage, with greatly-increased strength... and then die shortly afterward.
* Sol Badguy from ''VideoGame/GuiltyGear'' has a special called Dragon Install where he gains speed, power and extra abilities. If it reaches its time limit in the game, Sol gets temporarily weakened and the opponent will have an opportunity to attack. In the main story this is actually Sol's true form. His PowerLimiter is the only thing keeping his human appearance and sanity although recently it's losing it's effectiveness.
* The protagonist of ''VideoGame/{{Galerians}}'' is a [[PhlebotinumPills pill-popping]] psychic. One of the drugs causes his powers to go out of control, steadily draining his health in the process. Seems like PressXToDie, right? Not if you want to make a lot of mook [[YourHeadAsplode heads explode]] instantly and you have the antidote on hand...
* The [[http://www.hearthhead.com/card=846/power-overwhelming Power Overwhelming]] card in ''VideoGame/{{Hearthstone|HeroesOfWarcraft}}'' gives a minion +4 attack and +4 health until the end of the turn, which is a fair amount. At the end of the turn, said minion dies. Horribly.
* ''VideoGame/WorldOfWarcraft'' has the shadow priest talent ability Surrender to Madness, the character gives their soul to the [[EldritchAbomination Old Gods]], drastically increasing their insanity generation. The next time they enter voidform, they have until they run out of Insanity and then they die instantly no matter what and can't be resurrected by anything, not even spells that normally can raise in combat. But since their insanity generation is so drastically increased, and they get a full percentage of haste every second they remain in voidform, the priest is likely to have many of their spells nearly instant cast with no global cooldown, making them the strongest DPS in the game before the rate of expenditure overtakes the extra insanity generation and kills them.
* ''Franchise/TheElderScrolls''
** Becoming a [[OurLichesAreDifferent Lich]] is a very literal case of the trope. Mortal sorcerers, often {{necromancer}}s, undergo a ritual that turns them undead while [[WitchSpecies greatly increasing their magical power]] and also gives them [[ImmortalitySeeker the undead form of immortality]]. This is common among the senior members of the [[TheOrder Order of the Black Worm]], a reclusive MagicalSociety who mainly study TheDarkArts, following in the footsteps of their leader (and first ever Lich), Mannimarco, the King/God of Worms.
** As most prominently seen in ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'', [[BarbarianTribe Reachmen]] warriors may choose to become "Briarhearts." A [[HarpingOnAboutHarpies Hagraven]] will remove the warrior's heart and replace it with a Briar Heart, a magical organic object which looks something like a pine cone. The Briarhearts receive a massive power upgrade at the cost of free will and thought. They also pick up the WeaksauceWeakness that if the Briar Heart is stolen (say, by a skilled pickpocket) or damaged (say, by a skilled archer), they will fall dead instantly.

[[folder:Web Comics]]
* Near the end of the Nailbat story in ''Webcomic/AntiBunny'' Nailbat [[spoiler:begins trading off the last of his lifespan for enhanced physical abilities, and in the climax flight.]]
* ''Webcomic/ElGoonishShive'': Nanase's [[http://www.egscomics.com/?date=2009-10-03 Angel spell]] (see page image) very nearly became this because it allowed her to keep using magic well past her natural limit. The first time she cast it, she needed to be hospitalized, and although she eventually made a full recovery, her magic was completely burnt out for months.
* ''Webcomic/ProblemSleuth'' gained wings, glowing armor, superpowered weapons/writing implements, and access to insanely potent attacks upon using [[LimitBreak Sepulchritude]], however, once his Ink of Squid Pro Quo (which powers Sepulchritude) ran dry, he was left helpless, nearly paralyzed and at the [[GoIntoTheLight brink of death]].
* In the webcomic ''Webcomic/{{Mindmistress}}'', the title character uses a piece of AppliedPhlebotinum that grants her Braniac-level intelligence. But if she leaves it active for too long, it will leave her with brain cancer, if not killing her outright.
** Similarly, Dauntless, a super-hero imbued by her, must detransform periodically or his enhanced nervous system will cause him to overload on sensory input.
* Noetic Chiasm's Meristogenous Transgression was developed by Meander, the main character of ''[[Webcomic/TenPercentPlus 10%+]]'', to help counteract his tendency for his mind to wander; it allows him to focus his full attention on multiple things at once (which proves ''very'' handy during his battle against Rule). Downside? Putting that much stress on his mind will (and does) cause brain damage.
* In ''Webcomic/GirlGenius'' [[McNinja Smoke Knights]] sometimes use combat stimulants. A severely wounded subject under Movit #6 can [[PsychoSerum run around and fight, grinning maniacally]] for a few hours. Movit [[UpToEleven #11]] "[[http://www.girlgeniusonline.com/comic.php?date=20101013 would kill almost anyone]]" on its own. When one opponent is using this to CurbStomp everybody, it turns out the best way to bring them down is to give them ANOTHER dose, thus dangerously overclocking the dangerous overclocking to a level even they can't handle

[[folder:Web Original]]
* Recoil from the ''Roleplay/GlobalGuardiansPBEMUniverse'' had the power to absorb electromagnetic energy and use it for his own purposes. His absorption had no upper limit, but the more energy he took in, the more damage he suffered. When Doctor Devastation unleashed a superweapon that used an electromagnetic signal to trigger autosuicide in some 30% of the human population, Recoil wrapped himself around the broadcaster and set his absorption power to [[HeroicSacrifice "Go Ahead And Kill Me, But I'm Stopping The Signal."]] And he did. And it did.
* In ''Machinima/RedVsBlue'', The Red's Warthog get's a literal one; It gains a powerful and potent EMP cannon capable of disabling any electronic equipment it hits with a single blast. The downside is that, since the car itself is electronic; every time they fire it, the engine stalls. Simons even pointed out the downside before they upgraded.

[[folder:Western Animation]]
* On ''WesternAnimation/JusticeLeagueUnlimited'', The Flash goes really, really, ''[[LudicrousSpeed really]]'' fast, and ends up nearly pulled into another dimension, communing with a quasi-mystical "[[TheLifestream speed force]]" [[MythologyGag that was the source of his power in the comic]].
* One episode of the ''WesternAnimation/MenInBlack'' cartoon had Agent Jay accidentally use an intelligence-improving device that would eventually [[YourHeadAsplode cause his head to explode]]. After using his new brain (and the RippleEffectProofMemory that comes with it) to deal with a time-traveling villain who was erasing the founding members of the Men In Black from history, Jay managed to fix it by hijacking the baddie's time machine and [[TemporalParadox preventing it from happening in the first place]].
* In the second season finale of ''WesternAnimation/{{WITCH}}'', the heroines must unleash "their dragons within", literally becoming the [[ElementalPowers elements water, fire, earth, air, and quintessence]]. Because water, fire, earth, air, and quintessence aren't human, the girls lose their humanity as a consequence, and must be brought back to normal by their loved ones after the end of the fight.
* In ''WesternAnimation/TransformersAnimated'', [[spoiler:Sari, after the RoboticReveal, uses her Key to upgrade herself and try to fight the asteroid monsters. As soon as the fight is over, though, she loses control of her body and starts destroying everything around her, despite her best efforts to stop, including accidentally stabbing Bumblebee when he gets too close and nearly offlining him.]]
* ''WesternAnimation/AvatarTheLastAirbender'' has this with the Avatar state. It's a SuperMode that gives the Avatar the combined skills of all the previous Avatars, making him/her nearly invincible. Downsides are that it's hard to control without training (very bad since it turns the Avatar into a PersonOfMassDestruction), and if the Avatar dies in the Avatar state, then the Avatar's cycle of rebirth will end and the Avatar will cease to exist.
* In ''WesternAnimation/TheLegendOfKorra'' it is revealed that Aang had used the avatar state so much between his 100 years in the iceberg and his adventures afterwards his lifeforce was drained and he died at the biological age of 66(for reference, one of Aang's close friends from before his icebath was in fighting shape at 112 and the last avatar to have a natural death died at ''230'').
* [[ShapeShifter Beast Boy]] from ''WesternAnimation/TeenTitans'' [[InvoluntaryTransformation transforms involuntarily]] into The Beast in the episode "The Beast", which he from then on is able to become at will. Said beast is incapable of higher thinking and liable to attack the other Titans, but possesses strength beyond that of his teammates and SuperSpeed.
* WesternAnimation/DannyPhantom uses the ecto-skeleton in Reign Storm to defeat [[NamesToRunAwayFromReallyFast Pariah Dark]], but at the cost of 95% of his life energy. He gets saved just before burning through the last of his energy by [[BigDamnVillains Vlad Plasmius and every other ghostly opponent he ever had.]]
* ''{{WesternAnimation/Motorcity}}'': Kane has his employees invent a chip for his soldiers that makes them fearless, despite his scientists warning him it could be unstable. The cowardly Chuck finds this chip on one of the soldiers and takes it for himself. This does allow him to become more confident and stronger, but also causes him to rage out, including against Mike, his best friend. [[spoiler:Mike convinces him to remove the chip.]]

[[folder:Real Life]]
* Anabolic steroids are well known for their ability to make us stronger, etc. The downside is that there are a HUGE amount of side effects, not the least of which are heart problems, cancers, "[[UnstoppableRage roid rages]]," [[ArsonMurderAndJayWalking and man-boobs]].
** ''Sometimes'' TruthInTelevision. Not all anabolic steroids and analogues are that dangerous when taken in controlled amounts to help with recovery after surgery (assuming they're pure, and illegally-obtained drugs often aren't). Others are suffering in liquid form, inviting the physiological side affects mentioned above and others, as well as significantly increasing the risk of manifestation of psychological disorders in those with pre-existing conditions.
* The body uses another steroid, cortisone, to reduce inflammation and pain, which it does by suppressing the immune system. It is primarily released during periods of stress, which accounts for consequent illnesses. And any pain inhibitor in general is risky, as pain normally prevents someone from causing injury to themselves.
** This is likely the cause of what most students experience in the form of the post-finals flu.
* The vast majority of psychostimulants leave the user in a "smoking ruin" state by the time they wear off; mostly due to straight metabolical overload, so the more performance enhancement given, the more damage caused (''usually'' not permanent). Exclusions (like the Eleutherococcus group) work by rising power throughput and more adaptogenic with useful side-effects than stimulating.
* Adrenaline. The body's own flight-or-fight system normally doesn't pump enough of it to harm you. However, combine it with certain heart conditions and you will not survive. Also, ''external'' doses of adrenaline are not so limited and can cause your heart rate to skyrocket, or even a myocardial infarction. And this isn't even getting into adrenal disorders like Adrenaline Overload (as some doctors call it), which is basically the flight-or-fight system activating randomly and not turning off for a while.
** Adrenaline's pain killing properties and its "tunneling" of sensory perception can also lead to people injuring themselves much more often then usual. This is considered "worth the risk" from an evolutionary standpoint, as whatever damage it does is better than failing in a life or death situation; unfortunately, seeing that the conscious mind cannot control the flow of adrenaline, people often enter this mode when it is completely inappropriate for the situation, with potentially harmful results.
** Also, increased strength from adrenaline rushes (like a mother lifting a car off her child) is capable of causing serious damage to the body. The muscles, tendons, and ligaments aren't built to take a beating like that on a regular basis, which is the main reason your body only allows superhuman feats of strength under the most absolutely necessary conditions.
* In short, most of the above substances work a bit like taking out a loan from a loan shark. It gets you what you need, when you desperately need it, but the terms of repayment are ''absolutely awful''.
* Chechnya was this when it became an independent nation back in 1991. This caused Russia to have a full scale war that killed a lot of people against the country and annexed it as a republic of Russia.