Set a Mook to Kill a Mook

This is predominately a gaming trope, but may pop up elsewhere. In gaming, this is a specific type of Standard Status Effect.

In a lot of games, there's a way for the heroes to trick the baddies into fighting each other.

With Mecha-Mooks like robots and gun turrets, this is typically accomplished by "hacking". Usually this involves creeping up to them and using a skill or playing a minigame, or finding a computer terminal which controls their AIs. Less commonly, a special ranged attack might scramble their circuitry, or a called shot might take out their "differentiating between friend and foe" chip.

For Mooks made of meat, games may offer a wide range of charm, confusion, berserk, and possession effects. These are typically used to whittle a large group of foes down to one guy, who will probably be injured and wondering what the hell just happened.

In some games, a Mook who gets injured will immediately and deliberately return fire on all offending parties without any influence on the player's part. In these games, it is sometimes possible, through speed and agility, to trick bad guys into picking fights with each other in the best traditions of the Circular Firing Squad. If it is impossible for one mook to injure another (even accidentally,) that's Damage Discrimination.

Note that this only includes situations contrived or exploited by the player. If a stupid enemy simply keeps bouncing grenades off an obstacle and standing there as the grenades explode at its feet, that's Artificial Stupidity. When different preexisting factions of Mooks fight each other as well as the player character, that's a Melee a Trois.

Compare Let's You and Him Fight, the non-videogame equivalent.

Video Games
""The temporary illusions of the turncoat spell makes the target attack it's friends as if they were hated foes. Oh delicious remorse.""
 * In Halo: Combat Evolved, on the level Keyes,, a HUGE amount of flood forms rush into the room. It's overwhelming, unless you realize you can open the door to the next area, which causes an equally irritating Covenant spec ops team to enter the room. Then hide in the back corner while the two sides waste each other.
 * Military discipline amongst the Pfhor must be very lax, as Doom-like tactics of friendly fire-induced infighting are a staple of Marathon gameplay, Halo's predecessor series, made even more exploitable by a lack of Doom's species and ranged limitations, plus a number of preexisting grudges. Inducing such brawls in the Marathon series is eased by the fact that most enemies fire slow-moving projectiles. This tactic is probably the only reason the game is even winnable on higher difficulty settings.
 * Might and Magic games had mind-control magic which occasionally worked as advertised. Most monsters were immune to it, however, and it needed to be cast from quite a distance for the monsters to start attacking each other instead of you.
 * Might and Magic VII had monsters that could fight each other, humorously allowing you to slaughter the entire village in the beginning of the game, because you happened to lead the entire dragonfly hoard to the peasants and their unstoppable army of two guards
 * The Freedom Force games include every one of the above-mentioned effects.
 * System Shock 2 features hackable gun turrets.
 * As does its Spiritual Successor, Bioshock.
 * Bioshock also has the Enrage! plasmid, which causes the target to berserk and attack anyone else near them.
 * It's also possible to do this with Big Daddies, with completely hilarious results.
 * Bioshock 2 has Hypnotize, which has the same effect, but can also be charged up to get an enemy temporarily on your side. Especially useful if used on Brute Splicers and Prototype Alpha Series.
 * Fallout 3 has hackable turrets and security robots. Also, if you shoot insects in the antennae, they go berserk and attack each other.
 * Fallout 3 also has the Mesmetron, a special unique weapon that can cause human characters to go berserk and start shooting at everyone nearby.
 * The DLC Broken Steel offers several opportunities to take control of Deathclaws and unleash them on unsuspecting Enclave troops. This is sweetly ironic, because the method in which it is done takes advantage of the technology the Enclave was using to subdue these beasts in the first place.
 * The Knights of the Old Republic games offer many opportunities for this, mostly related to hacking and reprogramming droids and automated defense systems, as well as Force Confusion for the non-hackable targets.
 * In Half Life 2 you can, with the help of Alyx Vance, hack turrets and rollermines. When the former comes into play, you know you're about to get pummeled; when the latter does, you know there's a bunch of enemies coming up when you don't have a weapon yet.
 * Ratchet and Clank has a special weapon that causes enemies to fight against one another.
 * Artificial Stupidity kicks in when enemies who aren't doing this begin accidentally shooting each other.
 * Psi Ops features the ability to take over another enemy soldier and clear out a path for you without damage to yourself.
 * Second Sight featured a similar ability to possess enemy soldiers and use them to fight. Humorously, soldiers would continue fighting each other even if you stop possessing a soldier, as the other soldiers don't know he's no longer possessed, and as far as the formerly possessed soldier knows, his colleagues are shooting at him for no good reason.
 * The first three Oddworld games. In the first game, and for most of the second, possessing enemies is Abe's only form of attack. In the third, Munch can also possess robots by hacking the computers that control them.
 * The Deus Ex games feature turret-hacking, as well as “scramble grenades” that turn robots to your side.
 * With a bit of finesse, you can also get a lot of people very mad at a vacuum cleaner. (Look for Fun with Simons.. and UNATCO)
 * The Bind spell in Eternal Darkness turns an enemy against its allies. There are a few places where you have to use this in order to make enemies behind a barrier kill each other.
 * In Mass Effect, the AI Hacking skill temporarily makes geth (or other robotic enemies) attack each other. In addition, on Ilos there are armature repair stations that can be hacked to make the geth armatures attack other geth.
 * Its sequel lets you do the same thing to organic enemies as well with Dominate, Morinth's bonus power. If you have AI Hacking as well, then you can pretty much make any enemy in the game do your bidding for about 20 seconds.
 * In Psychonauts, using Confusion Grenades on enemies causes them to infight. It's particularly effective on the giant Censors, who then proceed to pound the crud out of all the littler enemies.
 * Iji: A terminal late in the game can give you direct control of a Komato Annihilator.
 * In Final Fantasy V, this is one of the easier ways to kill those dang Skull Eater squirrels: by taking over their minds with the Control ability from the Trainer class. You... have them eat their own skulls. No, I'm not sure how that works.
 * Similar powers exist in Final Fantasy VI (“Control” – which requires Relm or Gogo to wear the Fake Mustache Relic) and Final Fantasy VII (“Manipulate” – an ability granted by Manipulate Materia). In all three games, they can be very useful when trying to learn Blue Spells/Lores/E. Skills.
 * The Confusion powers from City of Heroes and City of Villains. However, you get less experience for mooks killed by those that are confused.
 * On the other hand, (as of Issue 11) it's possible to Confuse without being spotted (and therefore targeted), even by the affected party after the effect wears off, and so it can be used to wear down groups whose attention a character couldn't possibly survive.
 * It also works against players and in PVP.
 * This was a major feature of Doom, although not made explicit through any particular power-up or ability. It was implemented in quite a simple way: when fighting multiple enemies of different species, bait them into accidentally hitting an enemy of another species. This can be very useful in the hands of a skilled player.
 * The first level of Episode 3 of Doom, Hell Keep, starts you with a pistol and not much ammo with which to gun down all the imps in the first courtyard. Fortunately, it's easy to set up them up to shoot up or get killed by the cacodemons in the next room.
 * An important note is that same-species infighting never happens among projectile throwing monsters. This also extends to the fact neither the Hell Knight or the Baron of Hell can hurt themselves or each others' species with their green plasma balls [getting damaged is what causes infighting to start].
 * However, bullet/hitscan shooting enemies of the same species like the zombified humans and the Spider Mastermind are fair game to each other.
 * Even more so, Archviles will never receive retaliation from other monsters (or other Archviles, which can be hurt by the radius damage of their attacks) even if the Archvile directly attacks one with its sight-required immolation blast, but it is quick to go after any monster that can hurt it, ending it in a world of pain. Of course, being it's an evil healer, it can just resurrect the demons it kills after doing its job.
 * In Level 8 of Doom 2, one room contains a Cyberdemon, a good sixteen Barons of Hell and four Invincibility power-ups - grab an Invincibility and get the Cyberdemon's attention, then watch the battle royale ensue. Near the beginning of Level 20, a pair of platforms lower to reveal a Cyberdemon and Spider Mastermind which promptly attack you, though the level seems designed for you to trick them into fighting each other.
 * In fact, the Spider Mastermind seems designed to use monster infighting as his downfall; his main weapon is a chaingun which will provoke attack from anything else it hits -- even other Spider Masterminds. In addition, once he begins firing he will fire continuously at the target even for a few seconds after it has left his view. This allows the player to make himself a target and then run behind another enemy who will invariably be caught in the crossfire. Because of its rapid-fire weapon and high damage rate, the Spider Mastermind is best defeated by using its gun to provoke other enemies, letting them get a few counter-hits in, then attacking the Spider Mastermind while it is busy dealing with the new target. Trying to take one down while standing in the open trading fire is a sure-fire way of committing suicide most of the time (because Spidey's chaingun is a hitscan weapon and cannot be dodged).
 * Destroy All Humans! has the “Protect” command on hostiles in the first two games, and later the Zombie Gun.
 * The Beast Master class in Final Fantasy XI is able to charm animals and monsters into fighting other enemies, including their own kind.
 * The Venomancer class in Perfect World allows you to tame beasts to fight for you as Pets.
 * This is more or less the effect of a Frenzy spell in The Elder Scrolls.
 * A ring of conflict does this in Nethack; unfortunately, it also makes peaceful or friendly monsters attack you.
 * Nethack also features a variety of ways to turn hostile creatures into pets (and mounts!), including the Charm Monster spell and Scrolls of Taming.
 * Nethack also allows the player to tame certain animals by feeding them.
 * The “Steal Heart” Thief ability in Final Fantasy Tactics can charm one of your enemies into turning on his or her team. In an interesting variation, it only works on humans of the opposite sex from the user, but works on any and all monsters, which has some strange implications, at best. Additionally, Orators can talk enemies into actually joining you so you can recruit them after the battle.
 * The monster thing is a side-effect of monsters counting as opposite gender of humans for the purpose of zodiac bonuses.
 * This is quite fun to do in the 3rd Grand Theft Auto game. Unless two mooks are specifically on the same side, any mook will attack the mook that attacked it last (or run away). You can often offend someone into attacking you, and then getting the police to kill them for you (or the other way around).
 * In GTAIV, you can call the police on your mobile/a police car radio to report crimes in progress. Call them while engaged in a public firefight and they'll send squadcar after squadcar as your enemies mow them down (the cops themselves are fresh out of the ISM Academy). You can't join in the fight, though.
 * Blue Dragon has an interesting take on this: the player can highlight multiple types of enemies within the encounter circle on the world screen before initiating combat. If they dislike each other, once on the battle screen the enemies will attack each other in a "Monster Fight", and until their antagonist is eliminated they'll completely ignore the player characters.
 * The FPS Requiem: Avenging Angel had the resurrection power, which allowed you to revive killed enemy soldiers to fight on your side. Notably, the power had no limits to it (other than requiring an intact, non-gibbed body), allowing you to essentially create your own personal army out of all the killed enemy soldiers in a level.
 * Clive Barker's Undying had a similar resurrection power, but it was rather weak since it could only work on one enemy at a time, and resurrected enemies would crumble to dust after a couple dozen seconds and also had a random chance of turning on you and attacking you.
 * Of course, the same spell only works on monsters. If used on a living person, it only lets you give one type of order.
 * The free-roaming sandbox FPS Postal 2 does this in a humorous way that seems to be social commentary on gun control. Basically, almost everyone in the town of Paradise carries a gun. If a citizen sees someone opening waving a firearm, they'll draw their own firearm and open fire in self-defense. The catch is, when several citizens draw their guns at once (i.e. in response to you firing into the air), they'll regard each other as a threat, and start shooting each other in self-defense. This can quickly escalate into a full-scale war between every citizen in the current map zone of town, especially when the police get drawn into the shootout as well.
 * The third level of the Jedi Mind Trick in Jedi Outcast and Jedi Academy from the Dark Forces Saga will turn an enemy soldier to your side for a couple dozen seconds.
 * In Star Wars: Empire At War: Forces of Corruption, you can bribe enemies into being on your side, though this doesn't work on everyone.
 * In Final Fantasy Tactics Advance and its sequel, the charm status effect has the result of making anyone inflicted with it attack their allies.
 * In Final Fantasy XII Revenant Wings one of the best strategies for a certain boss battle is to make two groups of mutually antagonistic mooks fight each other while you sit back and bolster your forces to take on whichever battered group wins. It does require you to exploit several skills such as Haste and Invisibility, but it's far better than playing the battle as intended.
 * The Psychosis Gun in Perfect Dark. It's rather memory-intensive, however. It can only be used in one mission and is not included in the All Guns cheat.
 * It does have its own cheat specifically for its use in any mission, though. Unfortunately, the Infinite Ammo cheats don't apply to it, and you only get 4 shots. And the one or two mooks on your side will probably get mowed down by the 5 or so you fight at a time anyway.
 * Toward the end of the Subway level in Perfect Dark Zero, there's an option of stealthily shooting either a member of Killian's gang or a dataDyne soldier and causing a firefight.
 * The Condemned series. If two enemies are in the same room together and they don't see you, they will probably attack each other instead of standing there. And you can angle yourself so if two enemies are attacking you one might hit the other one and they will attack each other. It makes sense in context, since all of your enemies are insane homeless poeple who don't have any loyalties to anybody.
 * In World of Warcraft, Priests have Mind Control, which is pretty straightforward. It lets you take control of a hostile humanoid character for about 30 seconds or until the Priest takes damage a minute, though it can break earlier and damage done to the Priest will reduce its duration.
 * World of Warcraft takes this one past mooks: one boss in Naxxramas is built on this trope. Said boss hits so hard he's untankable -- but conveniently enough, his students not only can be mind-controlled, but have the exact skill-set necessary to tank and survive his assaults. (In ten-man versions of the encounter, the raid can't rely on having two priests, so instead two mind-control crystals sit conveniently nearby. One wonders how the boss didn't see this coming.)
 * There are actually several achievements for having a boss kill their lackeys by positioning them properly.
 * Metal Gear Solid 4's cleared game gives you access to the non-lethal emotion bullets, one of which enrages enemies into attacking anything nearby, be it friend or foe.
 * This was one of your viral powers in the Area 51 FPS game. Unfortunately, it was almost completely worthless since it used up almost your entire viral power meter, enemy Mooks did almost no damage to each other, and the Mook affected by it would only last several seconds before dropping dead of massive organ failure.
 * Fable has a sort-of version of this in the form of the “Summon” spell, which summons a spectral version of a weak monster. If that weak monster kills an enemy, it assumes that enemy's form and goes on to attack other nearby enemies.
 * Also, the shade can take the form of some rather powerful enemies, notably in The Lost Chapters, one can get a shade of Thunder, the 7 foot tall greatsword wielding optional boss.
 * If you play a character from the Ventrue or Tremere clans in Vampire: The Masquerade: Bloodlines, you can mind-control any random NPC into killing your enemies for you. If you're a Ventrue you can do the same thing through special dialogue options. Malkavians can also turn mooks into insane berserkers, or give them delusions or hallucinations that make them kill (you can, for instance, convince a Russian mobster that he is a grizzly bear and his two friends are salmon. Hilarity Ensues.)
 * If you have a high charisma stat, you can also play characters from various factions against eachother, though this isn't always a good idea (you can talk one of the thin bloods into trying to kill Nines or La Croix, for instance, but if you do, they will slaughter the thin blood and then be rather cross with you next time you talk to them.)
 * This is also in Final Fantasy VIII with its confusion spell. It's played for laughs in the fight with Biggs and Wedge at the beginning of the second disk. Casting confuse on them will invariably have them beating the ever-loving crap out of each other, yelling at each other to stop. Hilarity Ensues. This is actually one of the better ways of dealing with them.
 * In some of the Romance of the Three Kingdoms video games, there will be a “Mislead” or similar tactic where a general will attempt to trick an enemy general into fighting an ally, with one or both units taking damage. Since the success or failure of the tactic is usually based on Intelligence, and the damage done is based on a War or Leadership stat, many of the dumb ox officers can be hilariously lethal to their own side. Never, ever stand too close to Zhang Fei or Lu Bu if the enemy has a sharp “strategist” officer hiding in the back.
 * The Necromancer's Confusion curse in Diablo 2 causes enemies to attack randomly, and of course can be used on a crowd to turn them against each other. There is also the Attract curse which causes all enemies to attack the cursed target. Necromancers can also raise defeated enemies from the dead as their minions.
 * Paladins have an attack that temporarily makes an enemy switch sides. If Defeat Means Friendship, a good punch to the face means a brief alliance?
 * Splinter Cell. Often a soldier will be patrolling an area near a turret. Why the computer that controls the turret is always left unattended isn't explained, but you can sneak up to the computer and switch off the mechanism that allows it to tell friend from foe, causing it to open fire on the hapless mook(s.) You can then turn the turret completely off and explore the area as needed.
 * In Portal, when you are in a room with more than one turret, you can cause one to shoot down another. The victimized turret will actually respond to this with alarm, saying things like “Don't shoot!” and “Hey! It's me!”. This is an especially important strategy since you have no way of attacking them directly.
 * Left 4 Dead 2 uses this with the Bile Bomb, which mimics the effects of the Boomer's vomit. Splashing this on any zombie will cause a horde to swarm and attack the zombie(s) that have been hit by the Bile Bomb. Hitting the Tank with this earns you the Septic Tank achievement and Hilarity Ensues as you watch it being mobbed by its own kind. Don't try it on the Witch...
 * If you splash the bomb on two special infected, they will also duke it out to the death for more hilarity ensuing. Bile Bombs in VS mode is a major annoyance to the infected players since their screen gets covered in bile like they were vomited on by a Boomer and all the common infected will swarm the player and beat them to death.
 * The hilarity stops ensuing if a Boomer vomits on someone, negating the effects of the bile bomb.
 * In Rise and Fall Cleopatra has a special power which makes enemy units around here switch to her side, when they switch they instantly start to attack what was their own army.
 * In Prototype, the “Patsy” ability allows you to accuse others of being you as long as you're wearing a military disguise. Any other military in range will gladly gun down your target, then curse their screw up. You can even do it for them without punishment.
 * In Champion Of Norrath and its sequel, there are two spells like this: Convert for the living, and Convert Undead for the undead. They are learned by the high elf cleric and dark elf shadow-knight.
 * In the turn-based strategy Incubation, there's an enemy called Cy'Coo who has a devastating artillery attack, which is nevertheless slow: it takes it one turn to aim, and another turn to fire. Very clever players can have the Cy'Coo to aim at one of their soldiers, then move that soldier away and trick an alien into walking on the soldier's former position…
 * In The Immortal, you can turn two trolls against each other by throwing a troll ritual knife (used by trolls to declare a fight to the death) in between them, allowing you to sneak by them while they fight.
 * Metroid Prime has this once in the Phazon Mines, where you shut down a force field separating some Space Pirates from a horde of Metroids. As long as you don't draw their attention, they'll kill each other for you, maybe leaving one Metroid behind.
 * The game manual for Fur Fighters even suggests this strategy. They even completely ignore the Player Character so it's possible to attempt to create an all out mook brawl!
 * Averted in Odium - the enemies won't attack if their attack would hurt an ally (or themselves). Which means you can protect yourself from some wide-range attacks by standing next to an enemy (preferably a tranquilized or frozen one...)
 * In the 2005 King Kong games, you can get enemies to attack each other by manipulation of the food chain. If there's a number of different species in an area, then the larger ones will attack and kill the smaller ones. Megapedes are particularly prone to this, as they attack each other regardless of what the player does.
 * In Assassin's Creed: Brotherhood, you can use the  to cause mooks to fight each other
 * Minecraft lets you do this with skeleton archers. If they shoot at you and one of their arrows hits another enemy, a fight to the death ensues. Creepers actually drop a special item if they're killed by skeletons. In the Nether, the easiest way to kill zombie pigmen is to trick a fire-spitting ghast into blasting them.
 * In The Incredible Hulk: Ultimate Destruction, tanks will always fire a round if Hulk crosses their sights - but they disregard any other tanks in their line of fire. One of the mini-games actually places Hulk in a map full of respawning tanks with all of his attacks disabled, challenging you to survive while tricking the tanks into destroying each other as long as you can.
 * In Star Wars Shadows Of The Empire, Wampas have some pretty good items (for the early game at least) tucked away in their cages. When released, they will go for the closest attackable target. This is usually the player, but can just as easily be an enemy. Thus, the easiest way to get the special weapons they guard is to set them free, then dash out of the room and close the door. The Wampas will immediately turn on each other and, once they are finished, only one (injured) Wampa will remain.
 * And in Jedi Knight II: Jedi Outcast, and its sequel Jedi Academy, you can use the Jedi Mind Trick on enemies. At higher levels, they will see Jedi and Republic soldiers as friend and fellow Imperials as foe. Also, there are predators that attack everyone, so you can lure bad guys into the path of Rancors or and other monsters, sit back, and watch the fun. And by fun we mean "smashing, destroying, and devouring."
 * In Marvel Ultimate Alliance, there are a few ways to temporarily turn enemies to your side (using Spider-Woman's special attack and a powerup from the Enchantress), but the most reliable is Doctor Strange's Mind Wipe. It only lasts a few seconds, but when used on large enemy groups it's deadly. In the optional CD missions, the easiest way to beat the bosses of the Asgard maps is to lure a few score trolls and clay warriors to the end of the level, have them surround the boss, and then spam Mind Wipe. If used correctly, the boss will be pummeled to death in seconds.
 * In Plants vs. Zombies, the plant "Hypno-shroom" will cause the zombie that eats it to turn back and attack its fellow zombies in its lane until the hypnotized zombies are either eaten by other zombies or left the yard.
 * In some versions of Phantasy Star, Androids have Confusion Traps at their disposal, and some weapons can inflict Confusion with their Secondary Fire Special Attack. The Trap variant can affect a fairly sizeable group of enemies in one go, potentially leading to chaos as half a dozen Mooks suddenly start pounding on each other. This can be a welcome breather when badly outnumbered to say the least.
 * Dungeon Keeper; I'll just let the Mentor say it.

- The Mentor


 * One of the purposes of the paint mechanic in Epic Mickey is to turn Blotling enemies against each other by turning them into Mickey's allies.
 * In Borderlands, luring different groups of enemies together will often cause them to start fighting each other; an example being: triggering a group of skags to attack while being near a group of bandits may cause them to start fighting, especially if the bandits accidentally shoot the skags while trying to hit you.
 * In Evolva, the genedisruptor beam allows you to make enemies fight against them. Unfortunately, your enemies can do the same thing.
 * This can be induced with the Charm status ailment in the Tales (series), though thanks to Health Damage Asymmetry, it's mostly useful for getting enemies to ignore you temporarily.

Mythology

 * In the legend of Jason and the Argonauts, Jason defeats an army of soldiers grown from dragon's teeth by throwing a rock into their midst. In the manner of a cafeteria food fight, each believes the others have betrayed them, it snowballs, and they quickly slaughter each other. This makes this trope Older Than Feudalism.

Tabletop RPG

 * This is a common use for “Charm Person,” “Charm Monster,” “Suggestion,” and similar spells in Dungeons and Dragons.
 * Though it does not guarantee success. The creature perceives you very favorably and can often be convinced to do things which are dangerous or out of character. Smart DM's make the players actually play out that use of Charisma, making this much less effective as a combat spell, and downright devastating out of combat.
 * “Confusion” and “Chaos” do have the effect of making the affected mindlessly attack whoever's nearest to them, like say their own allies (they also act confused in other ways, but this is one of the major ones.)
 * Dungeons and Dragons 4th Edition's “fey pact” Warlocks are good at making it difficult for enemies to discern between friend and foe. Their highest-level powers involve full-fledged domination.
 * The House of Mirrors spell in Unknown Armies makes everyone else present see everyone as the spell's target. Trigger-happy enemies can easily end up gunning each other down if they don't realize what's happening.

Toys

 * In the climax of the 2008 Bionicle webserials, a group of Bohrok sleeping in the Archives of Metru Nui are awoken to take out the oncoming enemy horde of Rahkshi.
 * And way back in 2003, when the Bohrok-Kal were introduced, Tahu led a swarm of reprogrammed Bohrok to take down Nuhvok Kal. Unfortunately, they were launched into space by Nuhvok-Kal's gravity power. The Rahkshi Kuhrak also uses its Staff of Anger to turn its foes against each other.

Web Comics

 * In Order of the Stick, Xykon uses a
 * In Kid Radd, G.I. Guy uses a skill to possess a bunny that called more bunnies faster than the heroes could defeat them. After using the bunny to attack its allies, he made it commit suicide, prompting a What the Hell, Hero? from Radd.

Literature

 * This turns up a couple of times in The Bible:
 * Judges 7: Gideon, after having his 32,000 men pared down to 300 by weeding out the ones without good defensive instincts, gave each man a pitcher with torches inside and a shofar and told them to do like he did. When they reached the edge of the Midianite camp, he blew his shofar, and the others did the same, and they all broke their pitchers and shouted, "''The sword of G-d and of Gideon!" This set the Midianites fighting each other and fleeing.
 * 1 Samuel 14: Jonathan and his armorbearer went up to fight the Philistines, reasoning that God is just as good at saving His people through a few as He is through many. By the time Saul and the 600 with him reached the battle, he found that the Philistines were fighting each other in their confusion.
 * In both cases, the trick was to wreak so much havoc that the defenders would be tricked into thinking that they had a much larger enemy to deal with than they actually did. (The “friendly fire isn't” principle is why the uniform was eventually invented.)

Film

 * Mal Reynolds kites a massive armada of reavers to fight an equally-massive armada of Alliance in Serenity. His aim is to keep the Alliance busy so that he can.
 * Lampshaded and Averted in Rustler's Rhapsody. As the villains move to surround him, Rex says "You know, the way you've positioned yourselves, when the shooting starts you're liable to miss me and hit each other." The badguys look nervously at each other and them move back to their original positions.

Fan Works

 * In With Strings Attached, Ringo easily lures thousands of monster-starved skahs warriors down to the abandoned city of Ehndris and, later, to the Vasyn warehouse, where they are promised monsters in abundance. They joyously pile into the Raleka guarding the warehouse, allowing John and Ringo to get a head start in breaking into the warehouse via the roof.
 * Also, in New Zork, Paul escapes the “Hitler Youth” by causing hundreds of screaming Beaglemaniacs to swamp them.