Random people reinforcing the protagonist(s) or the opponents for the final battle, for no apparent reason other than to increase the magnitude of the fight. A less predictable version of The Cavalry or just about any Deus ex Machina.
In a streetfight or Escalating Brawl, it can take the form of thugs and random quarrelers joining both sides of the fight just because, often not even knowing the reasons of the brawl or what is actually happening, and with the sole intention to break further mayhem.
- The Whitebeard War was heading this way in One Piece. Every single Marine who ever appeared in the comic was there, plus a ton more. A bunch of New World pirate captains. The surviving male members of Baroque Works. Buggy the Clown. A small army of escaped prisoners and transvestites. Blackbeard and crew. However, it wasn't until Shanks and Trafalgar Law showed up that this really proved to be the case.
- The end of the second season of Vandread featured lots of people coming to Nirvana's aid against the Earthling(s). Although this wasn't really expected, it has been justified by all of them coming from planets where Nirvana's crew did something good or otherwise impressed the locals over the course of the two seasons.
- Indirect version in Tengen Toppa Gurren Lagann. During the final battle with the Antispiral, after a wormhole or something opens up to Earth, every single human being on Earth is seen believing in Team Dai-Gurren to take down the Antispiral. Remember, Spiral Power comes from belief and determination, both of which the entire population is supplying Simon and co. with.
- Marvel's "What If?" #34 (first series, an all-humor issue) had "What if everyone who had been an Avenger remained an Avenger?"
- The last scene in Monty Python and the Holy Grail, in which King Arthur's small band of knights suddenly becomes a huge army.
- Subverted in The Matrix Revolutions, wherein the 9 BILLION copies Agent Smith made of himself just stand around and watch Smith 1.0 and Neo fight.
- In Casino Royale (1967), everyone from the British army to Cowboys and Indians show up for the last battle. There is no reason for this. (Nor, really, anything else in the film).
- Similarly, the brawl at the end of Blazing Saddles is between all the bad guys and all the townsfolk and spills out into adjacent studios. A baker shows up in the studio commissary and hands out custard pies to the brawlers "for the big pie fight", even though he'd had no idea of knowing there was going to be a fight of any kind.
- In the climax of The Grand Budapest Hotel, Dimitri shoots at Zero and Gustave from one balcony inside the titular hotel. A random hotel patron steps out of his room with a gun and fires back, to be joined by several more on each side, and within seconds the entire room is a mess of chaos and gunfire as a dozen random combatants fire back and forth at each other for no particular reason without hitting a damn thing.
- The Blues Brothers, Inverted. While the police have been chasing Jake and Elwood for the whole film, at the climax, hundreds of police men, SWAT team, soldiers, tanks, and helicopters show up out of nowhere in downtown Chicago to apprehend two unarmed men.
- Parodied in both Anchorman: The Legend of Ron Burgundy and Anchorman 2: The Legend Continues with the "Battle of the News Networks", both of which consist of random news teams (and, in the second, supernatural entities) coming out of nowhere to join in the battle.
- Harry Potter and the Deathly Hallows - everybody and their dog shows up for the Battle of Hogwarts.
- Possibly overlaps into Gondor Calls for Aid, since a lot of the people who showed up were called upon to be reinforcements.
- Diana Wynne Jones actually does this a lot in many of her books; Howl's Moving Castle is probably the best known.
- The Battle of Five Armies in The Hobbit. First, the dwarves and the men are about to start a battle. Then the wood elves show up with their own claims/demands (but these are largely compatible with those of the men, so it's still essentially 13 dwarves vs. men and elves). Then Thorin's cousin Dáin from the Iron Hills arrives with a proper dwarf army at his back. After a very small amount of that they all at least temporarily put aside their differences to fight the goblins. The eagles appeared later and started doing a Death from Above thing on the goblins.
- Of course, the real Game-Breaker here was Beorn, who showed up at the last hour and pretty much singlehandedly destroyed half the goblin army.
- Parodied in the Monty Python's Flying Circus sketch "The Pantomime Horse is a Secret Agent Film."
"My goodness me, it's the Duke of Kent to the rescue..."
- In Glee almost everyone in McKinley joins the glee club right before a competition so they have enough members to compete. In Season one, Jacob Ben Israel briefly joins to replace Finn, but he doesn't actually compete. In Season two, Lauren joins at Puck's persuasion. And in Season three, the band guys join right before Sectionals.
- In Final Fantasy IV, the entire inactive party prays to revive the entire felled party at the end of the game, just prior to fighting the surprise final boss. And each member appears to say a line to the party in the process, to boot.
- Even dead party members show up to offer words of encouragement.
- EarthBound while fighting the Big Bad, the only way to beat him is to use the up until then useless skill "Pray," which causes all the NPCs in the world, plus the player, to pray together, which destroys the Big Bad.
- The citizens of Station Square did this in Sonic Adventure. Though how they were cheering, let alone alive, after the city had been destroyed is beyond anyone.
- Played literally in Castle Crashers where after you defeat the final boss, you and the princess ride on the crystal back to your castle. The final scene in the game before your princess turns out to be a clown, comes back to the party from the first scene only now filled with just about every character in the game, all having fun and drinking.
- Neverwinter Nights 2: Mask of the Betrayer has the final confrontation taking place in your own mind as it is being devoured by the Spirit-Eater curse, as you fight you call your allies and friends (some of which are dead) to assist you.
- Jade Empire won't let your party members join you in the final showdown, but they (those who remained loyal anyway) will help you take out the Big Bad 's minions.
- Majesty, you (as the sovereign) are not allowed to have certain groups, usually of warring religious factions, in your kingdom at the same time. However, in the final quest, as your kingdom's map gets filled out by exploring parties, they stumble across hidden pockets of every conceivable group of adventurers — all of whom promptly join in aiding you in the final battles against every villain you've encountered up to this point in the game. All the heroes versus all the villains, including the ones they already killed.
- At one point in Disgaea 3: Absence of Justice a show of support from Mao's friends goes overboard into silly when every minor opponent up to that point shows up to lend their support.
- When you're facing down Feinne the World Eater in Soul Nomad & the World Eaters for the second time, after she's annihilated the town everyone laments how you cannot hope to defeat her power. Cue textbook Big Damn Heroes moment as the knights of Raide and Christophe's mercenaries show up to lend their aid.
- Avatar: The Last Airbender, when the Gang (not Gaang, as the Avatar himself was having a one on one battle with the Big Bad) shows up at Ba Sing Se looking for Iroh, they not only find him, they also find the rest of the White Lotus Society... which consists of all the great masters of the world that aren't directly loyal to the Fire Lord. Cue Curb-Stomp Battle against the occupying Fire Nation forces.
- X-Men: Evolution had an epilogue that featured practically every character from the series who could conceivably join the X-men.◊
- Arguably, all of Justice League Unlimited was this, being a show featuring dozens of superheroes as a sequel to a show featuring seven.