History Main / GeminiDestructionLaw

* ''Series/RobotWars'' entrant Gemini is the TropeNamer. If 50% of any competitor's weight was destroyed/rendered immobile, the competitor was counted out; for Gemini, which was [[TheDividual a clusterbot that split into two smaller robots after entering arena]], this required either '''completely''' destroying/immobilizing one of the two robots or destroying/immobilizing 50% of '''each''' robot. This rule was removed later. Later when it competed in ''Series/BattleBots'' both robots had to be immobilized for it to count as a knock out.

* The Twin Card in ''Anime/CardcaptorSakura'' needed to have both halves of it defeated at the same time, and Syaoran and Sakura found that attacking them separately was ineffective. Luckily [[{{Muggle}} Meiling]] had trained with Syaoran in martial arts and they were able to carry out a coordinated attack to defeat it.
* ''Manga/DemonSlayerKimetsuNoYaiba'' has the Upper Rank 6 demons [[BrotherSisterTeam Daki and Gyutaro]], who due to the nature of how they became demons count as TwoBeingsOneBody and, while they can separate to fight individually, they ''both'' need to be [[DecapitationRequired decapitated]] at the same time (or at bare minimum the other needs to be beheaded before the other can reattach their head) before they can be fatally injured.
* In ''Manga/TheLuciferAndBiscuitHammer'', one of the golems the beast knights had to fight as part of the evil mage's challenge showed up as a pair, and then some. One was a straightforward strong centaur like golem, the other a swarm of almost cute mook like minions. They beat them, but the next day the swarm showed up again, but slightly different, and stronger. This continued for several days, the Beast Knights knowing that they had to figure out the trick to making them stay down or their slow improvement would let them overwhelm the Knights. They deduced that they needed to kill all the golem's bodies for it to stop respawning, and that at least one body was hiding while the rest showed up to fight each day. Eventually one of the beast knights found it, killing it easily because since it hadn't been destroyed unlike the rest of the bodies, it never [[CameBackStrong came back strong]].

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* ''Series/KamenRiderFourze'': The Aquarius Zodiarts manages to be a one-woman version of this trope by having a pair of water jugs on her shoulders which can instantly heal any wound, including repairing the other jug if it's destroyed. Fourze has to use an attack which breaks both jugs at once to actually defeat her. The Gemini Zodiarts, meanwhile, is ''not'' this trope despite having two bodies: only one is real, with the other being an ActionBomb.
* ''Series/RobotWars'' entrant Gemini is the TropeNamer. If 50% of any competitor's weight was destroyed/rendered immobile, the competitor was counted out; for Gemini, which was [[TheDividual a clusterbot that split into two smaller robots after entering arena]], this required either '''completely''' destroying/immobilizing one of the two robots or destroying/immobilizing 50% of '''each''' robot. This rule was removed later. Later when it competed in ''Series/BattleBots'' both robots had to be immobilized for it to count as a knock out.
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* ''[[Literature/TheReckonersTrilogy Mitosis]]'': The titular Epic has the power of at-will duplication, with no "prime" copy. So as long as even one of him exists, he can have a hundred bodies again within a minute.
* In ''Literature/PercyJacksonAndTheOlympians,'' Geryon has three torsos, each with its own heart, which gives Percy some trouble fighting him. He winds up praying to [[TheArcher Apollo and Artemis]] for a shot that goes through all three. ([[FridgeLogic For some reason it never occurs to him to just try lopping off Geryon's single head with his sword]].)

[[folder:Tabletop RPG]]
* ''TabletopGame/DungeonsAndDragons'' 1st Edition supplement "Fiend Folio": The Cifal (Colonial Insect-Formed Artificial Life) was a monster made up of a [[TheWormThatWalks huge number of insects bound together into a humanoid form]]. It had 10 hit dice altogether, two of them being the binding energy that kept the insects together. If you did two hit dice of damage to it, the insects broke apart and fled. That is, if you did 20% of its total damage, it was defeated. Course, then you've pissed off a whole hive of moderately intelligent bugs, who, being demonic, are probably going to want revenge...

* New Destroyman in ''VideoGame/NoMoreHeroes2DesperateStruggle'' is a partial case. The Destroyman who can fly and [[LongRangeFighter attacks mainly through projectiles]] can revive the other Destroyman. The other one, who fights [[CloseRangeCombatant mainly through hand-to-hand combat]], has no such abilities. However, the one who can fly spends most of the battle out of reach, making it hard to actually finish him off first before the close-range one pummels you.
* ''VideoGame/AzureStrikerGunvolt'' features a Sumeragi Adept named Elise you must fight who splits into two bodies for her BossBattle. If you fail to destroy both bodies at the same time, the surviving one will revive the dead one to one-third health. This can get tricky despite Gunvolt's ability to tag multiple targets for his flash field since the frenetic nature of the fight means you can double tag one body and deal it more damage than the other, throwing off your timing. [[spoiler: Elise returns for a second fight at the end of the game, along with all the other adepts, revealing she actually possesses THREE bodies (the reason she survived to revive everyone else). Unfortunately for Gunvolt, this third body is immune to anything he can throw at her (and once the other two go down once together, she revives them ''both'' at half-health each), but fortunately, he’s not the only enemy of Sumeragi in the area.]]
* Subverted ironically with ''VideoGame/MegaMan3''[='=]s Gemini Man, who does split into two bodies but allows you to destroy each body in sequence instead.

* ''VideoGame/LufiaIIRiseOfTheSinistrals'' had a dungeon boss that split into two, one form being fire-based and the other ice-based, which had to be defeated simultaneously. When the party first fights it, they fight each body one at a time; it regenerates and laughs in their faces. So they split the party in half and two characters fight each body.
* ''VideoGame/FinalFantasyV'' has the Gargoyles that guard the tablets used in the Sealed Temple. Killing one will just cause the other to revive it; to defeat them, you must kill them simultaneously or prevent one of them from acting (such as by sending it berserk).
* In ''VideoGame/BetrayalAtKrondor'', this is how the undead evil warriors called Black Slayers are implemented[[note]]In [[Literature/TheRiftwarCycle the original novels on which this game is based]], the Black Slayers are more like conventional zombies[[/note]]. If a group of Nighthawks includes a Black Slayer, then all of them must be killed within a short time, or the dead ones - both Nighthawks and Slayers - will revive as Slayers.
* ''VideoGame/FinalFantasyVIII'' has the Propagators, four color-coded pairs of creatures hiding on the Ragnarok. To defeat each pair, you have to kill one after the other without getting into a fight with another Propagator of a different color in-between. If you do, the defeated creature is revived by its partner.
* ''VideoGame/TheLegendOfZeldaTwilightPrincess'': Shadow Beasts always attack in groups of 3 or more, and when only one is left standing it will let out a howl that revives the others. To defeat them you must use area attacks to take down the last two at once.
* ''VideoGame/Persona3'' has Chariot and Justice, a DualBoss fight where both targets have to be killed in the same turn, or else the survivor will use the Samarecarm spell to fully heal the other. The two bosses occasionally fuse together, and one may think to kill them in this combined form...however, this form endures attacks at 1 HP indefinitely if it sustains otherwise-fatal damage, so the bosses must be killed while separated.
* ''VideoGame/KingdomHearts358DaysOver2'' has the Crimson Prankster, which immediately splits itself in two. Destroying one of the copies just causes the other to revive it with the same amount of health that the surviving copy has. They both need to be whittled down until the last of the remaining copy's health can be shaved off before it can revive the first.
* ''VideoGame/SlayTheSpire'' features Darklings, black BlobMonsters that may appear during Act 3 and always come in threes. So long as at least one of a Darkling's allies survives, it will revive itself after one turn when reduced to 0 HP; all three must be dead at once to kill them for good.
* Old versions of ''VideoGame/DungeonCrawl'' had shedim, holy monsters which always came in pairs could revive each other if given enough time to do so.

* ''WebComic/SleeplessDomain'': Cassidy's power as the {{magical girl}} Flash Cut is to [[DoppelgangerAttack split herself into two halves]]. These clones are significantly less durable than Cassidy herself, but if either of them is destroyed, Cassidy herself reforms unharmed at the intact clone's location, and can continue to split herself for as long as she still has enough magic to spare. If both of her clones were destroyed at the same time, however, there would logically be no intact clones left to become her main body, and Cassidy wouldn't be able to reform. [[spoiler:Which is ''exactly'' what happens when Goops gets a monster to slash at both clones. Cassidy uses her DyingMomentOfAwesome to stab Goops's eye in retaliation before she disappears.]]

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* In ''Literature/PercyJacksonAndTheOlympian,'' Geryon has three torsos, each with its own heart, which gives Percy some trouble fighting him. He winds up praying to [[TheArcher Apollo and Artemis]] for a shot that goes through all three. ([[FridgeLogic For some reason it never occurs to him to just try lopping off Geryon's single head with his sword]].)

* ''VideoGame/Persona3'' has Chariot and Justice, a DualBoss fight where both targets have to be killed in the same turn, or else the survivor will use the Samarecarm spell to fully heal the other. The two bosses occasionally fuse together, and one may think to kill them in this combined form...however, doing so causes only one of them to be destroyed and the other to revive them, so they must be killed while separated.

* ''VideoGame/KingdomHearts385DaysOver2'' has the Crimson Prankster, which immediately splits itself in two. Destroying one of the copies just causes the other to revive it with the same amount of health that the surviving copy has. They both need to be whittled down until the last of the remaining copy's health can be shaved off before it can revive the first.

* ''Series/RobotWars'' entrant Gemini is the TropeNamer. If 50% of any competitor's weight was destroyed/rendered immobile, the competitor was counted out; for Gemini, which was [[TheDividual a clusterbot that split into two smaller robots after entering arena]], this required either '''completely''' destroying/immobilizing one of the two robots or destroying/immobilizing 50% of '''each''' robot. This rule was removed later.

Compare HydraProblem (cutting the hydra's head may make 2 more heads appear in its place), as well as KillOneOthersGetStronger, for another situation where simultaneous destruction is recommended. Contrast FromASingleCell.

Compare HydraProblem (cutting the hydra's head may make 2 more heads appear in its place). Contrast FromASingleCell.

* ''VideoGame/AzureStrikerGunvolt'' features a Sumeragi Adept named Elise you must fight who splits into two bodies for her BossBattle. If you fail to destroy both bodies at the same time, the surviving one will revive the dead one to full health. This can get tricky despite Gunvolt's ability to tag multiple targets for his flash field since the frenetic nature of the fight means you can double tag one body and deal it more damage than the other, throwing off your timing. [[spoiler: Elise returns for a second fight at the end of the game, along with all the other adepts, revealing she actually possesses THREE bodies (the reason she survived to revive everyone else). Unfortunately for Gunvolt, this third body is immune to anything he can throw at her, but fortunately, he’s not the only enemy of Sumeragi in the area.]]

* In some ''VideoGame/MegaManBattleNetwork'' BonusDungeon, there are some preset encounters containing (usually) three identical enemies with infinite HP regeneration and ability to instantly revive themselves if you take them out one by one. To win these fights, you have to kill all enemies with one attack at the same time.

In video games, this may be the gimmick of a particular kind of mook, or a DualBoss (or a WolfpackBoss).

* In ''Manga/TheLuciferAndBiscuitHammer'', one of the golems the beast knights had to fight as part of the evil mage's challenge showed up as a pair, and then some. One was a straightforward strong centaur like golem, the other a swarm of almost cute mook like minions. They beat them, but the next day the swarm showed up again, but slightly different, and stronger. This continued for several days, the Beast Knights knowing that they had to figure out the trick to making them stay down or their slow improvement would let them overwhelm the Knights. They deduced that they needed to kill all the golem's bodies for it to stop respawning, and that at least one body was hiding while the rest showed up to fight each day. Eventually one of the beast knights found it, killing it easily because since it hadn't been destroyed unlike the rest of the bodies, it never [[CameBackStrong came back strong]]

* ''WebComic/SleeplessDomain'': Cassidy's power as the {{magical girl}} Flash Cut is to [[DoppelgangerAttack split herself into two halves]]. These clones are significantly less durable than Cassidy herself, but if either of them is destroyed, Cassidy herself reforms unharmed at the intact clone's location, and can continue to split herself for as long as she still has enough magic to spare. If both of her clones were destroyed at the same time, however, there would logically be no intact clones left to become her main body, and Cassidy wouldn't be able to reform.

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[[folder:Web Original]]
* This is the schtick of a [[TheFairFolk fae archer]] the party of ''WebVideo/TalesFromMyDDCampaign'' runs across. He can separate his shadow from himself, which in addition to doubling his firepower means that whenever either his shadow or his real self is threatened, it can momentarily teleport to the other's location and then back again to dodge attacks. The only way to harm him is to threaten both his bodies at the same time.

* In ''VisualNovel/{{Tsukihime}}'', [[HumanoidAbomination Nrvnqsr]] [[TheDragon Chaos]] can only be killed if all [[NumberOfTheBeast 666]] creatures that make up his body are killed at once. If they are killed individually, he can instantly regenerate them. This fact makes him nigh-impossible to kill, even for top-tier fighters like Arcueid. But when Tohno Shiki, who has the Mystic Eyes of Death Perception, kills something, it ''stays'' dead, [[DeaderThanDead no matter what]]. So he's able to kill pieces of Nrvnqsr without them regenerating, which freaks the monster out.

* ''Videogame/FinalFantasyVIII'' has the Propagators, four color-coded pairs of creatures hiding on the Ragnarok. To defeat each pair, you have to kill one after the other without getting into a fight with another Propagator of a different color in-between. If you do, the defeated creature is revived by its partner.

* In ''Manga/TheLuciferandBiscuitHammer'', one of the golems the beast knights had to fight as part of the evil mage's challenge showed up as a pair, and then some. One was a straightforward strong centaur like golem, the other a swarm of almost cute mook like minions. They beat them, but the next day the swarm showed up again, but slightly different, and stronger. This continued for several days, the Beast Knights knowing that they had to figure out the trick to making them stay down or their slow improvement would let them overwhelm the Knights. They deduced that they needed to kill all the golem's bodies for it to stop respawning, and that at least one body was hiding while the rest showed up to fight each day. Eventually one of the beast knights found it, killing it easily because since it hadn't been destroyed unlike the rest of the bodies, it never [[CameBackStrong came back strong]]

In video games, this may be the gimmick of a particular kidn of mook, or a DualBoss (or a WolfpackBoss).

* ''VideoGame/AzureStrikerGunvolt'' features a Sumerugi Adept named Elise you must fight who splits into two bodies for her BossBattle. If you fail to destroy both bodies at the same time, the surviving one will revive the dead one to full health. This can get tricky despite Gunvolt's ability to tag multiple targets for his flash field since the frenetic nature of the fight means you can double tag one body and deal it more damage than the other, throwing off your timing. [[spoiler: Elise returns for a second fight at the end of the game, along with all the other adepts, revealing she actually possesses THREE bodies (the reason she survived to revive everyone else). Unfortunately for Gunvolt, this third body is immune to anything he can throw at her, but fortunately, he’s not the only enemy of Sumeragi in the area.]]

* This is a common gameplay trope with [[DualBoss Dual Bosses]] in [=RPGs=], usually involving one boss casting a revival spell on the other if they aren't defeated at the same time.
** New Destroyman in ''VideoGame/NoMoreHeroes2DesperateStruggle'' is a partial case. The Destroyman who can fly and [[LongRangeFighter attacks mainly through projectiles]] can revive the other Destroyman. The other one, who fights [[CloseRangeCombatant mainly through hand-to-hand combat]], has no such abilities. However, the one who can fly spends most of the battle out of reach, making it hard to actually finish him off first before the close-range one pummels you.