History Main / IncreasinglyLethalEnemy

* The ''Anime/RanmaOneHalf'' fan fiction ''[[https://jusenkyo.fandom.com/wiki/Relentless Relentless]]'' revolves around one of Happosai's sins (insulting a witch by [[PantyThief stealing her undergartments]]) coming back to haunt all of the cast in the manifestation of a summoned spirot that is [[ImplacableMan implacable]] and, worse yet, [[AdaptiveAbility capable of adapting]] to all attacks [[ItOnlyWorksOnce that can injure it]]. By the time the Nerima Wrecking Crew finally figure out a way to kill it with magic in the final act, it is every bit as epic a battle to put it down as [[WhyWontYouDie you would expect it to be]].

* The ''Anime/RanmaOneHalf'' fan fiction ''[[https://jusenkyo.fandom.com/wiki/Relentless Relentless]]'' revolves around one of Happosai's sins (insulting a witch) coming back to haunt all of the cast in the manifestation of a summoned spirot that is [[ImplacableMan implacable]] and, worse yet, [[AdaptiveAbility capable of adapting]] to all attacks [[ItOnlyWorksOnce that can injure it]]. By the time the Nerima Wrecking Crew finally figure out a way to kill it with magic in the final act, it is every bit as epic a battle to put it down as [[WhyWontYouDie you would expect it to be]].

* In ''Manga/JoJosBizarreAdventure'', Part 3, this is what makes Anubis such a threat to the heroes: Not only can he [[ItOnlyWorksOnce learn how to counter any attack done to him right after it connects]], but he grows faster and stronger each time he fights.
* A common problem in ''Manga/KumoDesuGaNaniKa'', especially with boss monsters. Since continual exposure to threats allows you to unlock resistance skills, Kumoko has to kill her foes quickly before they grow immune to what she's using. Fortunately this goes both ways, as Kumoko also grows in power as she fights.

* ''LightNovel/TheUnexploredSummonBloodSign'' has the second and third variants. A summoner can raise the power of their Material (summoned creature) over time. Additionally, Materials are divided into three classes (Regulation-Class, Divine-Class, Unexplored-Class), each significantly more powerful than the previous. Summoning 100 Regulation-Class allows Divine-Class to be summoned, and summoning 50 Divine-Class allows Unexplored-Class to be summoned.

* ''VideoGame/{{Warframe}}'': Garuda weaponizes this with her passive ability, ''Death's Gate'': The lower her health is, the more damage she does. So her playstyle is very much a high risk, high reward one based upon effectively managing her health with ''Blood Altar''[[note]]Immobilizes an enemy and restores friendly players' health[[/note]] and energy with ''Bloodletting''[[note]][[CastFromHitPoints Restores Garuda's energy at the cost of HP]][[/note]]. [[DifficultButAwesome When done correctly, though, anything between Garuda and her objective may as well be bugs fighting a blender]].

* ''VideoGame/{{Warframe}}'': Garuda weaponizes this with her passive ability, ''Death's Gate'': The lower her health is, the more damage she does. So her playstyle is very much a high risk, high reward one based upon effectively managing her health with ''Blood Altar'' and energy with ''Bloodletting''. When done correctly, though, anything between Garuda and her objective may as well be bugs fighting a blender.

* The final boss of "The Answer" chapter in ''VideoGame/Persona3FES'' [[spoiler: Erebus]] will use an attack called Dark Embrace periodically. Each time is is successfully used it will increase in damage until it becomes impossible to avoid a TotalPartyKill. It's more downplayed than other examples however because it's possible to prevent it using it at all by inflicting enough damage while it's charging. [[GuideDangIt Not that it explains that.]]

SisterTrope to the TimeLimitBoss (when failing to defeat them in time is an instant game over), BossArenaUrgency (when the area the battle's taking place in is getting more dangerous) and MetalSlime (which costs the player a reward if it isn't defeated quickly instead). SubTrope to GatheringSteam. Contrast TurnsRed. Compare StalkedByTheBell and TimedMission, which share a similar relationship to this and Time Limit Boss. If you need to clear away your enemies' support to make things easier, you may need to ShootTheMedicFirst and / or ShootTheMageFirst. Don't even think about attempting VictoryByEndurance on them. TheVirus (especially the zombieism variants, given that a lone zombie may not pose a great threat, but it will infect others if not re-killed) is often a meta example, as the longer it spreads the more victims fall to it (and the more of a threat it becomes).

SisterTrope to the TimeLimitBoss (when failing to defeat them in time is an instant game over), BossArenaUrgency (when the area the battle's taking place in is getting more dangerous) and MetalSlime (which costs the player a reward if it isn't defeated quickly instead). SubTrope to GatheringSteam. Contrast TurnsRed. Compare StalkedByTheBell and TimedMission, which share a similar relationship to this and Time Limit Boss. If you need to clear away your enemies' support to make things easier, you may need to ShootTheMedicFirst and / or ShootTheMageFirst. Don't even think about attempting VictoryByEndurance on them. TheVirus is often a meta example, as the longer it spreads the more victims fall to it (and the more of a threat it becomes).

SisterTrope to the TimeLimitBoss (when failing to defeat them in time is an instant game over), BossArenaUrgency (when the area the battle's taking place in is getting more dangerous) and MetalSlime (which costs the player a reward if it isn't defeated quickly instead). SubTrope to GatheringSteam. Contrast TurnsRed. Compare StalkedByTheBell and TimedMission, which share a similar relationship to this and Time Limit Boss. If you need to clear away your enemies' support to make things easier, you may need to ShootTheMedicFirst and / or ShootTheMageFirst. Don't even think about attempting VictoryByEndurance on them.

* Zombies usually qualify. A single zombie usually doesn't pose a big threat to a human; the trouble comes if the small number of zombies is allowed to multiply into a number too great for humans to deal with.

* A common misconception was that Broly from [[Anime/DragonBallZBrolyTheLegendarySuperSaiyan the 8th]] ''Anime/DragonBallZ'' [[Anime/DragonBallZBrolyTheLegendarySuperSaiyan movie]] had his ki continuously increase while he was in his Legendary Super Saiyan form, based on a misinterpretation of one line he said. In Dragon Ball Super, characters like Hit and Ganos were introduced who actually fit this better, continuously improving throughout the fight.

SisterTrope to the TimeLimitBoss (when failing to defeat them in time is an instant game over), BossArenaUrgency (when the area the battle's taking place in is getting more dangerous) and MetalSlime (which costs the player a reward if it isn't defeated quickly instead). SubTrope to GatheringSteam. Contrast TurnsRed. Compare StalkedByTheBell and TimedMission, which share a similar relationship to this and Time Limit Boss. If you need to clear away your enemies' support to make things easier, then ShootTheMedicFirst and ShootTheMageFirst. Don't even think about VictoryByEndurance.

SisterTrope to the TimeLimitBoss (when failing to defeat them in time is an instant game over), BossArenaUrgency (when the area the battle's taking place in is getting more dangerous) and MetalSlime (which costs the player a reward if it isn't defeated quickly instead). SubTrope to GatheringSteam. Contrast TurnsRed. Compare StalkedByTheBell and TimedMission, which share a similar relationship to this and Time Limit Boss. If you need to clear away your enemies' support to make things easier, then ShootTheMedicFirst and ShootTheMageFirst. VictoryByEndurance is definitely the worst way to fight one.

** Pokémon with the Moxie Ability. This Ability causes the Pokémon that has it to gain one stage of an Attack buff (about a 50% boost per stage) every time it knocks out another Pokémon. If not stopped, these Pokémon ''will'' steamroll their way through the opposing team, especially if they can naturally increase their Speed. Magearna's signature ability, Soul Heart, is a Special variant of this, meaning it cannot even be slowed by Intimidate. Furthermore, it triggers whenever another Pokemon is knocked out - Magearna not only does not need to score the KO by itself (for example, if another Pokemon was knocked out by poison or burn, or by another Pokemon's attack), but it also triggers ''if a teammate was knocked out'', making getting boosts incredibly easy to pull off.

[[AC: Puzzle Games]]
* In all ''VideoGame/PuyoPuyo'' games starting from the second one, there is a "Margin Time" mechanic. After the amount of time set in that mechanic (which varies between modes - for example, ''Tsu'' has a Margin Time of 96 seconds and later iterations of ''Fever'' have double the Margin Time), the power of all chains made is boosted. This bonus stacks up to a '''120x''' multiplier, upon which point even a lowly 1-chain can fill half the board with nuisance puyos. It goes without saying that, outside of extreme circumstances (constantly offsetting attacks but without countering, or players so bad and slow they cannot beat each other quickly) or by using a very low Margin Time value, it's difficult to even reach 2x.

* BonusBoss Lucifer in ''VideoGame/DevilSurvivor'' has to be defeated quickly once he goes into his second form, as he will periodcally cast Megidoladyne, an [[InfinityPlusOneElement Almighty-elemental]] spell that targets everyone in all of your parties on the map and does 50% more damage with each successive casting, until it inflicts [[TotalPartyKill four-digit damage in a game where player-controlled characters can each only have up to 999 HP]].

* High-level paladins in ''VideoGame/WarcraftIII'' have a shield that makes them invulnerable and a mass ressurection ability. If not neutralized quickly, they spend the fight unable to take damage and bring back half a dozen dead units at full health.

* In all ''VideoGame/PuyoPuyo'' games starting from the second one, there is a "Margin Time" mechanic. After the amount of time set in that mechanic (which varies between modes - for example, ''Tsu'' has a Margin Time of 96 seconds and later iterations of ''Fever'' have double the Margin Time), the power of all chains made is boosted. This bonus stacks up to a '''120x''' multiplier, upon which point even a lowly 1-chain can fill half the board with nuisance puyos. It goes without saying that, outside of extreme circunstances (constantly offsetting attacks but without countering, or players so bad and slow they cannot beat each other quickly) or by using a very low Margin Time value, it's difficult to even reach 2x.

** Similarly to ''VideoGame/WorldOfWarcraft'', all of the Savage mode raid-tier bosses have an enrage mechanic.
** Several bosses spawn adds that makes it harder to fight the boss, either by attacking the players or increasing damage output on the tank, or can give the boss a permanent buff if left alone.

** If for some reason the party takes too long and the boss does its ultimate attack but the party survives, the boss will just cast it repeatedly until the party is wiped.
** Inverted if you're fighting against some Extreme Primals unsynced and thus can kill them quickly. If you bring them down too fast, they'll become invincible and enrage anyway.