History Main / TurnsRed

* Being set in an MMORPG, the anime ''LightNovel/SwordArtOnline'' also features this trope. In "Aria in the Starless Night", when Illfang the Kobold Lord's HP hit 25% (15% in the anime) it was designed to toss its axe and shield aside and gain a completely different attack pattern by unsheathing its talwar...[[spoiler:which was changed to a katana in the full release of SAO, which [[OhCrap caused radical changes to its movement speed and skill-chaining capability.]]]]

* Quite a few bosses in the ''VideoGame/{{MOTHER}}'' series do this:
** The Carbon Dog from ''VideoGame/EarthBound'' transforms into Diamond Dog after he has taken some damage, gaining a noticeable Defense boost, twice the hit points, a Shield, and an attack that can [[StatusEffects diamondize]] party members.

* ''VideoGame/{{Ultrakill}}:

** ''VideoGame/MarioParty'': The boss fights in ''VideoGame/MarioParty9'', ''[[VideoGame/MarioPartyIslandTour Island Tour]]'' and ''[[VideoGame/MarioParty10 10]]'' use this trope when the bosses' health gets below half. They'll either attack/move faster or have new attacks. They'll also throw a tantrum as well.

** Fighting boss characters in ''VideoGame/MarioParty9'' and ''VideoGame/MarioPartyIslandTour'' uses this trope when their health gets below half. They'll either attack/move faster or have new attacks. They'll also throw a tantrum as well.

** In ''VideoGame/SuperSmashBros64'', while Master Hand himself didn't change in appearance as his HP lowered, [[AmazingTechnicolorBattlefield his stage did]]. The background starts as a night sky filled with shooting stars. When Master Hand's HP falls to 200, the shooting stars stop and poisonous-looking purple clouds fill the area. When it falls to 100, the background turns into a blue vortex. Each background change is marked by a slight power boost, the most obvious being that his FingerGun attack will fire three projectiles in quick succession instead of one during the vortex phase.[[note]]Incidentally, this unique trait makes Final Destination a nightmare to try to play normal matches on in ''64,'' even with a VideoGame/GameShark, much to the dismay of those into TournamentPlay; without a boss to connect the background to, it causes the game to crash unless even further hacks are applied. One workaround if not using a full-fledged GameMod is to combine codes to 1. skip to the final match of Classic Mode, 2. make the Player 2 character in Classic Mode human-controlled, 3. forcibly change Player 2's character ID, 4. change Player 2's stock count, 5. change the time allotted for Classic Mode battles, and 6. change the stage's music, as by default it will only play the ominous-sounding intro rather than the music track the stage is known for.[[/note]]
** In ''VideoGame/SuperSmashBrosUltimate'', once Galeem gets down to less than half-health, his core [[PowerGlows erupts with light]] like it's a star about to go supernova, [[spoiler:and once Dharkon gets down to less than half-health, his eye [[RedEyesTakeWarning changes color, turning the sclera from a bright blue to a deep red, his iris from yellow to a bluish-lavender, and his pupil changing to the color of his sclera]] as if it's bloodshot.]]

* In ''VideoGame/AlphaProtocol'', Brayko takes cocaine once you get his health down to 50% (and after that as a regular part of his attack pattern), which temporarily turns him into a knife-swinging, immune-to-stun-and-knockdown madman (well, moreso than usual) who runs supernaturally fast and will hunt you down and shank you. Just like in real life. If you have Steven Heck on your contact list, he will spike Brayko's drug stash which means Brayko doesn't get the speed bonuses and damages himself slightly every time he does it.
** Similarly, if you kill his bodyguards Conrad Marburg will flip out and hunt you down for a good round of fistcuffs until you damage him sufficiently again. Despite being a 50-year old man using his bare hands, he's almost as nasty as Brayko in melee.

* [[EvilTwin Sabata]] does this in ''VideoGame/{{Boktai}}''. Once you empty his life-bar he replenishes all his health, knocks out the lights, and gains a couple new attacks.

* The bosses in the first ''VideoGame/BreathOfFireI'' game will recharge a sliver of life, which takes more time and effort than the entire previous life bar to get rid of. The later games 'solved' this by hiding life bars of enemies you haven't beaten before.
** Some, in particular the Grimlin and Horntoad, would "get mad" at the party and ruthlessly spam hit-all magic attacks that became harder to cope with, as there was only one cure-all spell in the game (and it was unlikely the player would have learned it at either point in the game).

** In both ''[[VideoGame/CastlevaniaSymphonyoftheNight Symphony of the Night]]'' and ''[[VideoGame/CastlevaniaPortraitOfRuin Portrait of Ruin]]'', the [[OurZombiesAreDifferent zombie]] [[DeadPersonImpersonation doppelgängers]] imitating [[spoiler:Trevor, Grant, and Sypha from ''[[VideoGame/CastlevaniaIIIDraculasCurse Dracula's Curse]]'']] all gain new or stronger attacks when one of their allies fall in battle. [[spoiler:Sypha]] even gains the ability to re-revive [[spoiler:Trevor]], albeit as a shambling, mostly-dead shell.
*** In the battle with Richter Belmont, once his HP is halved, he'll immediately use Hydro Storm, and become stronger and more aggressive.

** Bloody Stunner Chiefs. Bloody Juicer Chiefs. Bloody Tanks. Bloody Clockwork Princes. Bloody explosive enemies. (Mages, I'm looking at you. Embalmed Vahzilok zombies, I'm also looking at you.) Quite a lot of the stuff I like fighting does this...

* In the ''VideoGame/GodEater'' series, Hannibal (and its more powerful variant Corrosive Hannibal) gains access to a new attack where it levitates and hits you repeatedly with pillars of fire when you break the scale on its back. Much truer to this trope, the Arda Nova (and its stronger variant) becomes much faster and gains access to a completely different moveset if (and it's difficult not to) you take down its male half first.

* ''VideoGame/IWannaBeTheGuy'' bosses love doing this. Kraidgief and Mecha Birdo are especially notorious for Turning Red, the former first trying to bash you and then throwing fireballs (along with a Kenshiro Spinning Piledriver if he gets too close), and then throws Blankas at you for the final phase; and the latter shooting egg platforms and Shyguys at you for the first phase, firing lasers at you for the second phase, and then going back to the Shyguy phase for the last leg, only the tips of the egg platforms in the last half kill you if you touch them.

* Emperor Sun does a version of this in ''VideoGame/JadeEmpire'' — however, instead of getting pissed, he gets desperate (complete with a cut scene showing his waning powers) and starts switching around his defences faster than before (ensuring the player has to change attack style with EVERY HIT in order to get around his immunities).
** Additionally, Master Smiling Hawk will magically drain the life of one of his followers when he hits half health, getting a couple of new fighting styles — and all his health back. (But he's not exactly hard to beat anyway!)

* Zakum in ''VideoGame/MapleStory'' goes through this twice. He has three health bars, and his sprite looks more and more damaged as each bar is emptied. The more damaged he is, the more he uses an attack that reduces everyone's HP and MP to 1. When he's down to his last health bar, he uses the attack constantly.
** Papulatus also turns red, although he only does it once. Although the second health bar has very little health and lacks his room-filling magic, he [[FragileSpeedster moves extremely fast]] and flies all over the room. Very deadly considering his CollisionDamage is enough to kill anyone in 1 to 3 hits.
* In ''[[VideoGame/MarioAndLuigiSuperstarSaga Mario & Luigi: Superstar Saga]]'', the last time Popple attacks you, he teams up with Birdo. If you take Popple out first, Birdo loses it and says "You may have defeated my darling, but [[CatchPhrase that is as far as you go]]!" then literally turns red and begins firing off her exploding eggs in a more random pattern.

* Speaking of SNK bosses, Allen O'Neil (an insult-spewing, machine-gun-toting, [[BaldOfEvil bald]] badass who shows up in most of the ''VideoGame/MetalSlug'' games) will turn redder and redder the more lead (or whatever) you pump into him. Then he [[NoOneCouldSurviveThat dies]], says "SeeYouInHell!", and [[UnexplainedRecovery recuperates in time for his next appearance]].
** What's more, the end of mission bosses of the ''Metal Slug'' series have a tendency to become more aggressive or use more weapons as they become significantly damaged; for example, the Keesi transport plane of mission 1 in ''Metal Slug 2'' starts off by dropping Arab swordsmen to attack you while not laying a finger on you itself, but as it gets a beating, it instead has two Rebel soldiers unload on you with rockets, and the plane itself will start attempting to incincerate you with its afterburners.

* In ''VideoGame/RuneFactory: A Fantasy Harvest Moon'', the bosses literally become a reddish tint and attack faster and stronger after certain HP depletion. Especially lethal since it's really easy to forget that this happens, and it throws off the timing you've established that far. It's the same in ''VideoGame/RuneFactory2''. In ''VideoGame/RuneFactory3'', the bosses begin to flicker black and gain an extra-powerful attack.
** ''VideoGame/RuneFactoryFrontier'' takes that up a notch during post-main story rematches against dungeon bosses if they have already been beaten at least twice. They will go through the entire match in "tinted" mode and can easily [[CurbStompBattle curb stomp]] your character if unprepared.

* The final boss of ''VideoGame/StreetFighterIV'', Seth, [[IAmNotLeftHanded handicaps himself in the first round]] by not using any of his special moves. If you beat him, he'll flash black on the ground, then stand up, levitate, and shout, "WITNESS MY LIMITLESS POWER!" In the second round, he'll go into total SNKBoss mode.

** [[spoiler:Bowletta]] in ''VideoGame/MarioAndLuigiSuperstarSaga'' turns black once damaged enough, assuming an entirely new attack pattern as well as becoming [[TheSpiny hazardous to jump on]].

* During the fight with [[spoiler:Belius]] in ''VideoGame/TalesOfVesperia'', she ''duplicates herself'' after taking a good chunk of damage, making an already hard boss battle into a controller-smasher. You can at least get rid of the Shadow version of the boss by relighting all the torches in the arena.
** Practically all of the bosses in the game and throughout the series in general start using new attacks as their HP lowers. They also have an unpredictable version of this in the games where they can activate Overlimit, as it temporarily lets them spam their attacks (On top of sometimes enabling the use of new ones), makes them ImmuneToFlinching, and permits the usage of their [[LimitBreak Mystic Arte]] if they have one.

* In ''VideoGame/{{Tekken}} 6'', all characters will enter Rage mode at low health, but the boss will actually begin to ''glow'' cherry red when he's losing, and can [[OneHitKill kill you with one hit]] you at that point.
** Speaking of ''Tekken'', Heihachi will do this in ''VideoGame/StreetFighterXTekken'', should he activate Pandora mode. Usually, the character who you're sacrificing to get Pandora mode will crumple up on the floor and the character receiving Pandora will become a purple/black mix. However, when giving Heihachi Pandora, he simply [[YouHaveOutlivedYourUsefulness throws his partner out of the ring]] and turns red.

* The last GUILT, [[spoiler:Savato]], that you have to fight in ''VideoGame/TraumaCenter: Under the Knife'' does this after you've separated it once. However, given that the game forces you into The Healing Touch at this point, it's the easiest part of the operation.
** Also, in ''Trauma Center: Under the Knife 2'', [[spoiler:Pempti, the mutated version, has two cores, destroying one quite literally causes the other one to turn red and go berserk with relentless attacks on the patient until it, or the patient, is dead]]. As well as this, [[spoiler:Aletheia, the final boss, has one last desperate move when you're almost done, blood vessels around the core flash red at a rate faster than the eye can keep up with; if you haven't got the Healing Touch ready to slow things down to a regular version of cut-all-8-blood-vessels-while-they-are-not-red, then you are screwed]].

* In ''VideoGame/WarioWorld'', Red Brief J gains more attacks and his charging attack becomes more lethal as he loses health. Captain Skull is a pushover until he loses half his health, in which case Wario's punches have no effect, and stunning him is much harder.

* Solidus Snake from ''VideoGame/MetalGearSolid2''. He's relatively easy at first, but once half of his health bar has been depleted, he says, "Very good, Jack, but this is where it gets interesting." He proceeds to shed his tentacles, begins spamming a lunging blade attack that leaves behind a trail of fire, and is generally much more aggressive.
** The Rays, once damaged enough, start using homing missiles and laser cutters.
* The Pain from ''VideoGame/MetalGearSolid3''. Once down to about half health, he takes off his mask, revealing his disfigured face. He then becomes more aggressive and unleashes his "Bullet Bees," [[BeeBeeGun poisonous bees that he shoots like bullets]]... from his mouth. It's a long story.

* ''VideoGame/{{Bloodborne}}'' has Lady Maria who is a competent boss with a nice moveset and a lot of speed. Once you get her to about half her health she stabs herself and uses her blood to increase the range of her hits, a la ''VideoGame/{{God of War}}''. Get her to about a fourth of her health and she does it again, increasing her range further and causing the blood to burst into flames, causing a lot of extra elemental damage. It's justified as Maria hates using blood magic, so she fights without it [[BatmanGrabsAGun until she fears]] that you might defeat her and unleash the secrets hidden in the Fishing Hamlet.

** The DLC's BonusBoss Laurence, the First Vicar, starts out on fire and moves on to his legs melting off, spewing lava all over the room.

* The BonusBoss [[spoiler:Spamton Neo]] in ''VideoGame/{{Deltarune}} Chapter 2'' has an interesting ''player-triggered'' version of this starting from the 1.6 version. During the fight, it's possible to chain together [[ChargedAttack "big shots"]] by holding the Enter key and pressing Z. The 1.6 patch changed [[spoiler:Spamton Neo]] so that, if you use this glitch, the boss notices and flies into a rage, massively increasing the boss's damage output.

* [[BonusBoss Baal]] from ''Franchise/{{Disgaea}}'' already has utterly ridiculous stats. However, if you kill off all the mooks in his stage before him, his stats (except for HP) double.
** All of the bosses from the spinoff PlatformGame ''VideoGame/PrinnyCanIReallyBeTheHero'' do this when you whittle them down to 25% HP. Regular enemies do this as you damage them, but their tactics don't change.

* Every boss from ''VideoGame/FinalFantasyXII'' will do at least one of: unlocking more powerful attacks, doubling their power and toughness (effectively meaning their lifebar is 150% long), or turning invincible(!) The only practical way to defeat some is to damage them to just above the threshold, and then unleash the characters' [[LimitBreak one-use-only ultimate combo attacks]] and pray. When applied to some of the game's [[BonusBoss wicked optional bosses]], things just get ridiculous.

** [[BonusBoss Enuo]] from the Gameboy Advance remake of ''VideoGame/FinalFantasyV'' does a somewhat subtle version of this when he reaches roughly half health; all damage dealt to him is halved and he begins using dangerous counter attacks. This isn't a visual change, but is rather indicated by the message "The power of the Void is increasing!"

** The BonusBoss[=/=]TrueFinalBoss Dark Matter does this in nearly every game it's in, too. One moment you're fighting a cloud of black smoke, the next you're [[NightmareFuel up against a giant bleeding]] ''[[NightmareFuel eye.]]''
** In ''VideoGame/KirbysReturnToDreamLand'' (and every traditional platformer in the series therafter), all of the bosses get serious and start using new attacks at half health, with a change in size and/or appearance often accompanying it. Some are more notable than others. The [[DiscOneFinalBoss Grand Doomer]] turns red twice: once normally, and a second time at low health that makes him NighInvulnerable. Only Super Abilities could damage him. The FinalBoss, [[spoiler:Magolor]], turns red FOUR TIMES for a five phase final boss fight after the traditional [[spoiler:UnexpectedShmupLevel]]. However, these phases are generally divided into two forms: The first three phases that work like the Grand Doomer, then a normal boss fight for the second form. The [[BonusBoss Bonus Bosses]], [[spoiler:HR-D3 and Galacta Knight]], both have very memorable Turning Red sequences. [[spoiler:HR-D3]] in the Extra Mode is actually a giant Turning Red scenario: [[spoiler:The Egg Engines Boss, Metal General, summons this robot after defeat in Extra Mode. HR-D3]] does not have any Turn Red scenarios in its health bar. [[spoiler:Because it is partially a CallBack to VideoGame/Kirby64TheCrystalShards, meaning it has TWO WHOLE healthbars.]] Then, we have [[spoiler:Galacta Knight]], who is even MORE of a BonusBoss than [[spoiler:HR-D3]], as he isn't even fought in the Extra Mode, but only in [[spoiler:The [[NintendoHard True]] [[BossRush Arena]]]]. He is fought EXACTLY like a normal boss, but instead of his theme from [[spoiler:Kirby Super Star Ultra]] playing, he gets [[spoiler:Landia's theme. Until he actually turns red. THEN his own theme music kicks in, he unleashes a combo, and starts using more deadly attacks.]]

** The {{Bonus Boss}}es love this:

* Certain bosses and [[BossInMookClothing unique monsters]] in ''VideoGame/XenobladeChronicles1'' will start busting out new attacks and/or activate an aura that grants them a substantial boost to their combat abilities when their health starts to dwindle. The latter can be removed by certain arts, while you just have to deal with the former. [[BonusBoss The Avalanche Abaasy]] does both, starting off using just auto-attacks and Ultra Play Bite, before going into Ultra Tail Strike, which is less lethal but hits in a fan shape and topples, into Demon Purging Fire which hits everyone doing Blaze and Paralyse while doing a lot of damage, into his talent art which will certainly OHKO any character without Monado Shield. After that it'll go Crazed, increasing his attack speed and damage while making him immune to topple, and when he only has 25% health left he'll go into Awakening, raising his level even further and making him even harder to hit.

* In ''VideoGame/KingdomHeartsII'', the Hot Rod heartless will charge in a berserker rage once their HP is low. Most times they strike you from where you're not looking. (This is a real pain at higher difficulties if you're at a lower level.)
** The Large Body heartless similarly go berserk at low HP and start bellysliding after you at an astonishing speed, but can be stopped by blocking and/or using a reaction command on them, unlike the previous example.
** The aptly named Berserker Nobodies also do this, repeatedly using an annoyingly long, unstoppable combo on you that renders them nigh impossible to hit with anything but magic while they're performing it, and only giving you a few seconds to land a combo of your own between each assault.

* The ''VideoGame/{{Kirby}}'' franchise has Scarfy, an enemy that looks like an adorable floating ball with wiggling cat ears. However, if you try to inhale it, or damage it without defeating it, it will take on a more monstrous appearance and start pursuing you. Previously it was stationary, if harmful. It can be defeated only by [[PowerCopying copy abilities]], sliding, or throwing something at it. It also has a penchant for [[ActionBomb blowing up]] after chasing you for a certain length of time.
** Scarfies were featured in ''Anime/KirbyRightBackAtYa'' as well, and naturally, trying to eat them didn't work there either.
** ''Kirby: Squeak Squad'' allowed you to [[DemonicPossession possess]] them, and by pressing B, they transform. The real kicker is that the minute you make the possessed Scarfy transform, they gain an ''intense'' speed boost compared to their originally calm pace, raging hastily through the area as you move it. If an enemy is unlucky enough to get in it's way, the impact can half the enemy's health, or ''kill it outright''.

* The BonusBoss [[spoiler:Spamton Neo]] in ''VideoGame/{{Deltarune}} Chapter 2'' has an interesting ''player-triggered'' version of this starting from the 1.6 version. During the fight, it's possible to chain together [[ChargeAttack "big shots"]] by holding the Enter key and pressing Z. The 1.6 patch changed [[spoiler:Spamton Neo]] so that, if you use this glitch, the boss notices and flies into a rage, massively increasing the boss's damage output.

** The DLC also has an ''inverted'' example (Turns Blue?) in [[spoiler: Ludwig the Accursed/ Ludwig, The Holy Blade. He starts the fight as a mindlessly aggressive monster, but when he gets to about half health, he'll scrape together what remains of his sanity to fight you like a swordsman.]]

** Bunches of bosses in the ''VideoGame/MetroidPrimeTrilogy'' do this too. Ridley is one notorious example, as are the guardian bosses from ''VideoGame/MetroidPrime2Echoes'' (Jump Guardian, Bomb Guardian, Spider Guardian...) and the final bosses of all three games ([[spoiler:Metroid Prime, Emperor Ing/Dark Samus, and DS/AU 313]]).

** ''VideoGame/DonkeyKongCountryTropicalFreeze'': Most bosses in the game. The fifth boss has an interesting justification. Every time you hit him, you knock him into a pool of juice, dyeing his fur darker each time.

* ''VideoGame/DynastyWarriors'' and ''VideoGame/SamuraiWarriors'' will sometimes have enemy generals, usually ones with unique models (IE, playable characters or at least important [=NPCs=]). When knocked down or in a defensive position, they may glow for a moment and suddenly buff themselves. They will also often glow for a few seconds before unleashing a [[LimitBreak Musou attack.]]
** ''Dynasty Warriors 5'' deserves special mention. On specific levels, specific characters will be tougher than usual (with a [[BattleAura red aura of doom]]). As they take damage, they give themselves temporary stat boosts (Doubling their Attack or Defense, for example), with the last buff ending in [[SuperMode Musou Rage]] (increased damage, attack speed, and super armor to all but the most powerful of attacks). Ignoring them while they have these buffs doesn't always work, either. They'll just get it again shortly after they run out.
* The BonusBoss of ''VideoGame/EtrianOdyssey 3: The Drowned City''. It starts as a massive, screen-hogging EldritchAbomination, which only turns out to be its ''bottom half''. And midway in the fight against its top part, it suddenly ''flares up'' with a roar, changes shape, and starts the next phase of the fight with ''plenty'' of beatings which can easily one-shot your entire party if you're unlucky.

** Death in ''VideoGame/CastlevaniaChroniclesOfSorrow'' will change slightly, with new and deadlier attacks. Then again, Death does this in other games too.

* In ''VideoGame/Fallout4'', [[BossInMookClothing Legendary enemies]] can "mutate", which restores their HP and gives them damage and defense boosts, sometimes literally glowing red.

** ''VideoGame/RainbowIslands'' does the same thing — leave them on the screen too long, or trap them under a rainbow without killing them, and they'll red up. In the unlockable NostalgiaLevel based on ''VideoGame/BubbleBobble'' itself, the original enemies are ''already'' red. Most have their attacks expanded, albeit ultimately [[CanonDiscontinuity canonically discontinuous]].

* {{Inverted|Trope}} in the NES version of ''Bubble Bobble '''Part''' 2'': In the ([[NintendoHard really hard]]) [[BonusStage bonus games]] which would otherwise be an UnexpectedGameplayChange, whoever loses the point to his opponent turns red.

** Fighting boss characters in ''VideoGame/MarioParty 9'' and ''VideoGame/MarioParty: Island Tour'' uses this trope when their health gets below half. They'll either attack/move faster or have new attacks. They'll also throw a tantrum as well.

* ''VideoGame/Pikmin2'': The Waterwraith, a humanoid blob of water attached to steamroller-like wheels, does this when you finally get a fair battle against it. When its health hits zero the wheels explode into dust and the "Boss Defeated" music begins to play, but then cuts itself off and flows into an eerie-yet-comical version of the boss theme while the Waterwraith, alive but disarmed, begins panicking and running around the arena, trying to get away from you. It can't even hurt you at this point, and chasing it down and killing it is [[ImplacableMan highly]] [[StalkedByTheBell satis]][[ParanoiaFuel fying]].

** Similarly, if you kill his bodyguards Conrad Marburg [[BerserkButton will flip out]] and hunt you down for a good round of fistcuffs until you damage him sufficiently again. Despite being a 50-year old man using his bare hands, he's almost as nasty as Brayko in melee.

** Queen B in ''VideoGame/DonkeyKongCountry1'' does this, zigzagging around the screen faster after every hit.
** Kruncha in ''VideoGame/DonkeyKongCountry2DiddysKongQuest''. Pretty much every boss in any of the ''VideoGame/DonkeyKongCountry'' games adjusts attack pattern progressively harder after ''each'' hit. King Zing Sting in ''2'' can't be hurt while colored red.
** Both Mugly and Thugly in ''VideoGame/DonkeyKongCountryReturns'' progress through [[RuleOfThree three stages]] as you fight them; both turn red and crank up their attacks in the third stage.
** Most bosses in ''VideoGame/DonkeyKongCountryTropicalFreeze''. The fifth boss has an interesting justification. Every time you hit him, you knock him into a pool of juice, dyeing his fur darker each time.

* ''VideoGame/DragonAgeOrigins'' has numerous examples, including the Broodmother (who's a real pushover until turning red and summoning lots of mooks) and [[spoiler:the Archdemon, who also summons mooks after getting down to about half health]].
** Special mention has to go to the Sloth Demon that [[spoiler:traps your party in the Fade in the Circle Tower (''Broken Circle'' part of the main quest)]]. Uses an especially annoying variation of the trope as he assumes a new form when brought to near 0 HP, each with progressively deadlier abilities - and fully regenerated health. [[spoiler:And he does this ''four'' times.]]

* One of ''VideoGame/FinalFantasyX'''s [[BonusBoss Bonus Bosses]], Neslug, retracts into its shell after losing enough HP, at which point it becomes impervious to any physical attack that isn't an overdrive, and has an irremovable Regen status that will restore craploads of HP, sometimes in the sextuple digits, [[TheComputerIsACheatingBastard never mind that your characters — and pretty much every other enemy — can only restore or inflict up to 99,999 damage with one hit]]. When and if the shell breaks (again, after depleting even more of its HP), Neslug loses its shell and resumes its out-of-shell attacks, only at a faster turn rate.

** Pretty much ''every'' boss in ''VideoGame/Klonoa2LunateasVeil'' goes into this mode, picking up a few new stunts. Then, when you kill the boss, [[MadeOfExplodium it blows up. Several times.]] But ''before'' it explodes, it turns red.
*** Bonus points for the fact that the health meters turn to a garish hot pink when it ''turns red''.

* The ''VideoGame/MegaManX'' series tends to like this. Starting from ''Mega Man X2'', you can pretty much expect bosses to do something nastier/cooler if they're more than half down on their health. Possibly another upgrade when they're down to a quarter.

* Pretty much every boss in the ''VideoGame/MegaManBattleNetwork'' series will start attacking more often, upgrade their usual attacks, and/or start using new attacks once their health hits the 50% mark.

** The final boss of ''VideoGame/{{Romancing Saga 3}}'' creates an eclipse in the background, gains wings, and draws power from one of the four Devil Lords. If you didn't kill at least one of the four Devil Lords before this fight, you're pretty much guaranteed to lose at this point — unless the party has nearly maxed-out WP and JP and you use the GameBreaker ([[spoiler:Zo with Dragon God Descent]]).

* Pretty much every boss in the video game adaptation of ''VideoGame/ScottPilgrimVsTheWorld'' start flashing gold once their health has been depleted past a certain point — mimicking the players' own Hyper Mode. They then get much faster and start spamming their strongest attacks.

* In ''VideoGame/{{Tekken}} 6'', all characters will enter Rage mode at low health, but the boss will actually begin to ''glow'' cherry red when he's losing, and can pretty much [[OneHitKill kill you with one hit]] you at that point.

* In ''VideoGame/WarioWorld'', Red Brief J gains more attacks and his charging attack becomes more lethal as he loses health. Captain Skull is pretty much a pushover until he loses half his health, in which case Wario's punches have no effect, and stunning him is much harder.

* The [[CyberNinja cyborg ninja]] from the first ''VideoGame/MetalGearSolid'' was incredibly impressive in combat up until you depleted most of his health, at which point he stuck to one feinting punch attack while crying desperately, [[DoesThisRemindYouOfAnything "That's it! Hurt me more! More! More!"]]

* Every boss in ''VideoGame/MuramasaTheDemonBlade'' does this multiple times, partially because they can [[DamageSpongeBoss soak up a LOT of damage]] before being defeated. Each time you knock a boss' primary health bar down to zero, it gets angrier and its attack pattern changes.

* Bosses in ''Manga/OnePiece: Unlimited Adventure'' do this, but [[PsychoElectro Eneru]] takes this a step further: after his HP is depleted, he restarts his heart (something he does in the original series), making you fight him [[HeadsIWinTailsYouLose all over again]] this time with more bolts of lightning falling from the sky.
** Rob Lucci does pretty much the same thing he did in series. After beating down his unassuming-looking human form, he uses the Cat-Cat Fruit (Model Leopard) and turns into a super-dangerous leopard-man.

* Zeromus, the FinalBoss of ''VideoGame/FinalFantasyIV'', spends most of the fight repeatedly bombarding the party with his devastating Big Bang attack along with Black Hole to nullify any status boosts. In his final phase, he switches to spamming the ultimate spell and DangerousForbiddenTechnique Meteor...and it's damage output is utterly pathetic. However, the DS remake plays it straight by making Meteor just as powerful as Big Bang, and he also uses Whirl on your entire party, an HPToOne attack which can automatically kill your entire party combined with the Sap status lingering from Big Bang.

** And now, there's two new types of bosses that turn red: "HardMode[=/=]WhatIf" Bosses and "Death Label" bosses. Hard mode bosses have secret forms/attack patterns that activate after the player does something, such as not dying or shooting the boss's tail. "Death Label" bosses are just the regular boss, just faster, deadlier, and maybe possessing more forms.