It doesn't seem that way in Neon Genesis Evangelion until it turns out that the Evas are clones of the Angels.
In Higurashi No Naku Koro Ni the heroes eventually need to call the Banken, a military group, for assistance against the weaker Yamainu.
Tower Of God: To dispose of Lurker, Ja Wangnan calls upon the help of the only guy who can help: an admitted religious fanatic and terrorist who proclaimed before that he'd fail everyone in the current batch of Regulars. The subversion kicks in the moment you remember that said terrorist is former main character 25th Baam, probably one of the nicest guys around.
In Slayers, Lina calls on power from Shabranigdo, the God of Evil, to defeat lesser monsters. Twice Lina calls on power from the Lord Of Nightmares. This is the Giga Slave spell, which, if miscast or if control is lost, could unmake the world. She's just that badass.
A definite example in Naruto is Manda, the giant snake. Orochimaru and Kabuto summon him to fight Jiraiya and Tsunade, but these summons have a tendency to be rather unreliable, and Manda is by far the worst; once demanding 100 human sacrifices to pay for his service. Considering Orochimaru lost his arms and was incapable of using jutsu, they were desperately hoping he didn't betray them . Ultimately, Sasuke summons Manda and mind-controls him to act as a shield against Deidara's ultimate jutsu. Manda is killed by the resulting explosion, effectively preventing any betrayal.
in Dragon Ball, Vegeta's still powerful enough to kill Goku, Krillin, Gohan and Yajirobe even after all the unGodly punishment he took in the climactic battle of the Saiyan saga. In a desperate gambit, Goku tells Gohan to look at the Power Ball in the sky, which transforms him into a raging, uncontrollable giant were-ape (oozaru). Initially, having lost all reason, Oozaru Gohan presents just as much of a threat to the heroes as Vegeta does, but Goku is able to telepathically communicate with him, and sics him on Vegeta.
In an early episode of Pokémon (The Ghost of Maiden's Peak), when Ash attempts to fight a Gastly using his Squirtle and Bulbasaur. The Gastly summons an illusion of Blastoise and Venusaur, and then goes so far as to combine them into Venustoise, turning his already bigger fishes into one sort of... biggerer fish. It's explained that the pre-evolved forms fear their fully evolved forms to an extent due to some kind of instinct. So making them bigger and more badass is going to cause them to panic.
Digimon Adventure had Tai force Greymon to evolve to defeat an opponent Greymon, resulting in SkullGreymon. Said SkullGreymon proceeds to kill the Greymon and run wild, blowing stuff up and curbstomping the other partner Digimon's attempts to restrain it.
In Digimon Tamers, Takato orders Guilmon, both enraged by the murder of Leomon, to evolve to the Ultimate form in order to revenge-kill Beelzemon. The result is Megidramon, whose very existence threatens to cause the Digital World to collapse... and Beelzemon thrashes him anyway. Then Guilmon gets a second wind and digivolves into Gallantmon and wins.
The fight between Marcus and Thomas in Digimon Savers, when Thomas betrays DATS, has their partners ShineGreymon and MirageGaogamon roughly equal in strength, and so an attempt by Marcus to invoke the more powerful Burst Mode is influenced by his rage at Thomas' betrayal; this results in ShineGreymon Ruin Mode, who runs wild before reverting to a DigiEgg; Thomas and MirageGaogamon are forced to retreat.
Digimon Xros Wars Taiki has access to DigiMemories which allow him to summon powerful digimon to use their special abilities, like Leviamon and DarkDramon.
In Hellsing we have the enslaved vampire Alucard who works for the Hellsing organisation hunting vampires. Since all vampires are a universally psychopathic, obsessive race who commit slaughter for fun and are almost unstoppable to a regular human, Alucard is no exception, except he has the power of a Physical God, and there is practically nothing that can stop him, with very few exceptions. In OVA III, he gladly shreds a small army of innocent police officers because they (correctly) thought that he was an insane serial killer. The only thing that differentiates him from a far more dangerous version of what Hellsing is fighting is that he's honour-bound to serve Integra, his master.
The World Government in One Piece get it in their heads that the only way to compete with the power held by the big wig pirates in the new world is to enlist the Seven Warlords of the Sea, who are essentially government sanctioned pirates, to fight for their side. So essentially, they're privateers. If you'll recall many of the most famous pirates started out as privateers and then were retconned into pirates by the governments withdrawing support. In One Piece, that happened backwards.
Quent in Wolf's Rain fights wolves with Blue... Who's a wolf. Well, half-wolf half-dog, but she looks exactly like one. To be fair, he also uses a shotgun.
Comic Books
When he's not being used as a villain, this is the major role played by Marvel Comics character Galactus — the Fantastic Four have summoned him to defeat cosmic villains like the Sphinx, his rogue herald Terrax, Hyperstorm, and Abraxas, and various space-based franchises have used the character for this as well.
Similarly, DC Comics often shows lesser superheroes calling on the Spectre when mystical evils get way out of hand. In most modern versions of the Justice Society of America, this is essentially the Spectre's role on the team.
Used in the Legion Of Super-Heroes V3 comics. The Time Trapper is, among other things, the Anthropomorphic Personification of the theory that the universe only goes 'round once. There's another villain, the Infinite Man, who is the embodiment of the theory that the universe runs on an infinite loop. Brainiac 5 brought in the latter to defeat the former.
In Blackest Night, when faced with a Black Lantern version of The Spectre, the heroes come up with the really desperate plan to sic Parallax on him (using Hal Jordan as his host once again).
Earlier, the Green Lanterns on Oa are overwhelmed by a Black Lantern swarm, so Guy Gardner decides to release a Red Lantern from the Oan prison and throw it at them. This works for about three panels before the Alpha Lanterns kill the Red Lantern for "escaping". And then the red ring goes after Guy.
In Hellblazer's All His Engines, John Constantine is charged with killing several demons. He succeeds by feeding them to an Aztec god.
Similarly, an early arc has a cult succeed in summoning a truly ancient dragon-god by creating a lesser fear-deity. In this case, the dragon-god summons itself to eat the lesser god.
John must really like this strategy. In the Dangerous Habits story arc, he's already pissed off the First of the Fallen, who's waiting for him to die of cancer, so John summons two other Lords of Hell and sells his soul to BOTH of them without the other knowing. Which leads to an early CMOA for Johnny, as he gets to flip off all three of them◊ and walk away smiling.
In the Season 8 comic-book continuation of Buffy the Vampire Slayer, Buffy and her slayers are depowered and must fight against the US Army. When all hope seems lost, Buffy summons the goddesses they had previously given their power to in a (ultimately vain) attempt to hide. The goal is two-fold: to have the ginormous goddesses attack the army, and to get their powers back. The plan backfires, however, as not only do the slayers not get their power back, but the goddesses attack both group indiscriminately. Buffy is finally able to defeat the goddesses after gaining Superman-like powers.
In one episode of De Rode Ridder (The Red Knight), fairy of light Galaxa does away with prince of darkness Bahaal by summoning what is hinted to be Satan himself. (Yes, De Rode Ridder is that much of a Fantasy Kitchen Sink.)
During the DC's Our Worlds At War storyline, in order help defeat the forces of Imperiex, Doomsday is released from the can Superman had sealed him in.
Umar is the sister of Dormammu, the Lord of the Dark Dimension. When she confronted Dr.Strange, he, on advice of the Ancient One (his mentor) freed the demon Zom to oppose her. Now, Umar is... pretty bad-ass. She and her brother are the only survivors of the race of energy beings, the Faltine, mainly because they destroyed all the others. She rules the bad half of the Dark Dimension, which is why she is pretty ornery most of the time. She once bedded the Hulk and... exhausted him to the point where he turned back to Bruce Banner and couldn't Hulk out again. She cracked the world in half rather than travelling around it to get to the Ancient One, the Sorceror Supreme and therefore the most powerful magician in the world, and defeated him soundly. That's how bad-ass she is. When she clapped eyes on the unleashed Zom - who automatically homes in on the most powerful magic-user in the vicinity - she fled like a startled deer, declaring she wouldn't leave the Dark Dimension ever again. Of course, Zom was in turn just as scared of the Living Tribunal, but the latter wasn't summoned, so he doesn't count.
In Nick Fury's files regarding Marvel's Secret War, he plans for a worst case scenario of open attack on Latveria that includes using Jessica Drew to control the Sentry and dropping the Hulk and the Punisher on either side of Latveria and seeing who reached the middle first.
In The Umbrella Academy, The Rumor's solution to a giant berseker Abraham Lincoln statue: A giant John Wilkes Booths statue, complete with a stone derringer. Afterwards, the Booths statue is seen escaping, with the police chasing after him.
Boxer decides the only course of action in the Godzilla ongoing IDW comic when Hedorah, Monster X, Space Godzilla, and Gigan attack Earth is to release the trapped Kaiju from Monster Island and free Godzilla from an experimental cage (though he frees himself first).
In the Jackie Chan Adventures and Teen Titans fic A Shadow Of The Titans, when Jade is sent to break Machete out of prison, only for it to turn into a fight with Raven and Starfire, Jade lets Cinderblock out of his cell in order to keep the Titan girls busy.
The Unity Saga contains an example, when Thrawn advises the Alliance (or, at that point, New Republic) forces to engage a third (& very hostile) party. He then orders them all to withdraw, at which point a Borg fleet, at his behest, decimates the third party.
Luminosity has Bella do this to establish her as a Guile Heroine. James is going to kill her, but has enough flair for the dramatic to leave her alive long enough to talk. She convinces him to take her to the Volturi, who rule vampires and don't like being disturbed.
The Pony POV Series has this pop up in the Dark World timeline. How does Apple Bloom's spirit manage to break Discord's control over Applejack? By getting one of the only four beings in existence stronger than Discord to help. While the Father of Alicorns doesn't simply overpower Discord's control, he's still wise enough to help Apple Bloom convince Applejack to change.
In The 10 Doctors, the Ninth Doctor utterly defeats the Black and White Guardian... by vworping into the same time/place location with so many selves that it summons the Time Dragons.
At the end of A Bug's Life, Flik actually summons the very bird that attacked him earlier in the film to kill Hopper.
Films — Live-Action
Clash of the Titans, as well as the legend of Perseus, was him using Medusa's head to defeat the kraken.
Although in the original Greek myths, it's a sea serpent (kraken are from Germanic/Norse myth and legend—they're in the movie because of Rule Of Cool).
Then again, it really isn't a Kraken either, just a big guy with tentacles on the back. They probably just liked the name.
The film The Lord of the Rings: The Return of the King has the capital city of Gondor under attack by a Badass Army of evil orcs and trolls. Fortunately for the good guys, Aragorn gets an Army of the Dead to come to the rescue. Given that there's no way to defeat the undead, some consider this a Deus ex Machina outcome.
There's also the Great Eagles who come in to save the good guy's armies from the Nazgul and their flying beasts.
Perhaps when the heroes teleport the giant rock monster onto the enemy starship in Galaxy Quest?
Arguably the tactic employed in the Pirates of the Caribbean films, when Calypso is summoned in hopes that she'll take out the East India Trading Company and Davy Jones.
The film Godzilla Final Wars pretty much uses this trope as its basic plot. Long story short-humans release Godzilla from imprisonment so he can fight the other giant monsters so that the humans can stop the evil aliens from destroying the world.
To be more specific, Godzilla didn't care about fighting the aliens, he was just chasing after a flying submarine/battleship that he fought before getting buried in a glacier, the humans knew he would follow it so they just lured him into where the other monsters were.
Quite a few of the Godzilla films had plots based on this trope. Godzilla Vs King Ghidorah did it twice: the humans release Godzilla to deal with Ghidorah, then Mecha-Ghidrah to deal with Godzilla.
Mal and his crew provoke a horde of Reavers to take on the Alliance in Serenity.Then it turns around and bites them in the ass when Wash is killed by the same Reavers, and the entire crew is badly wounded in the subsequent battle, only saved by River declaring You Shall Not Pass.
Though in the end the Alliance win, making this more of a "Summon smaller fish" or "Summon distraction".
And given that the Alliance created the Reavers to begin with Mal makes the case that the Alliance has to clean up its own mess.
The Operative: There's a lot of innocent people dying up there
Mal: You have no idea how true that it is
The title character in Constantine summons Lucifer to defeat Mammon and Gabriel.
The future San Angelenos in Demolition Man view the release of John Spartan like this. To them he's just as much a criminal as Simon Phoenix and his worldview and behavior is just as alien.
"Send a maniac to catch a maniac."
Boa vs. Python: Send a giant snake to kill a giant snake. For some reason. Apparently the plot doesn't make terribly much sense.
Pretty much the plot of The Chronicles of Riddick. The Necromongers, a strange cult of Omnicidal Maniacs, is threatening the Galaxy. What do the good guys do in response? Track down convicted killer Richard B. Riddick in the hopes that he'll take care of them.
Aereon:In normal times, evil would be fought by good. But in times like these, well, it should be fought by another kind of evil.
It worked because of a prophecy that foretold the Grand Marshall would be killed by a Furion, and Riddick is the last one there is.
Backfires horribly in Stargate SG-1 movie, The Ark of Truth. Merrick, on the orders of the IOA, plans to unleash replicators on the Ori ships, wait for the replicators to destroy the Ori, and then deactivate the replicators. Sam and Cam think this is a terrible idea; they're right.
The protagonist of Wishmaster 3 tries this by wishing for the aid of the Archangel Michael. It only partly works. Michael has a sword that can kill the Djinn, but only the summoner can actually kill the Djinn and can only use the sword once they become worthy. Michael spends most of the film with her running. Still, his healing powers are useful.
In Napoleon Dynamite, Napoleon sees a fellow student being bullied and tells him "Pedro (who is running for class president) offers you his protection." The guy thinks Napoleon's just trying to nab his vote, but sure enough, when the bully returns to steal his bike, Pedro's "cholo" cousins come to save him.
Literature
Daine attempts this in Wild Magic with an enormous kraken. Despite her apprehensions, it works out pretty well.
To clarify: Daine summoned it knowing that she wouldn't be able to send it away again - it's too powerful and - more importantly - too intelligent to be fully controlled by her wild magic. However, she took a calculated risk, keeping in mind that she had a pair of seriously overpowered magical allies, who were merely out of the game for a while. Sure enough, once they've recovered, they're able to 'convince' the Kraken to go home again.
The Dresden Files: At the end of Dead Beat, Harry is facing down a bunch of necromancers and an army of zombies. His solution? Animate himself a tyrannosaurus zombie and stomp the bad guys flat of course!
Later, in Cold Days, Harry is in an even worse bind as Queen Ladies Lily and Maeve are trying to unleash several Eldritch Abominations from their prison. To finally stop them, he summons Queen Mab who stops them with one sentence.
Same author, different series: In the final book of the Codex Alera, Tavi has to find a way to deal with the insanely dangerous Vord Queen, while at the same time she's putting a lot of effort into dealing with him. He just plain old can't face her head-on. So he flies up to the summit of Garados and deliberately irritates the Great Fury. Chaos ensues. But hey, it did work in the end.
In the Discworld book Guards! Guards!, after Wonse loses control of the dragon he summoned, Vimes encounters him planning to summon another one to fight it. (He's about 90% insane by then.)
This done with confidence tricksters is essentially the plot of Going Postal, where Vetinari uses Moist von Lipwig to work against Reacher Gilt. In this case his insurance is that Good Feels Good and by the time it's over Moist will have reformed sufficiently to no longer be a problem.
Also referred to in Making Money, where Moist explains that the mongooses were bred in the postboxes, to keep down the snakes; who were introduced to reduce the number of toads; which were put there to keep down the snails. The snails had gotten in on their own accord to eat the glue on the stamps, though. He admits that they "were a bit too creative in our thinking" though.
Near the end of Shiver, the protagonists determine that lycanthropy may be curable through elevating the victim's internal body heat to extreme levels, comparable to a massive fever. They attempt to do this by injecting two victims with bacterial meningitis Results? Mixed. One character is cured, the other dies from the meningitis.
Used in one Cthulhu Mythos story. The protagonists in the story are investigating a series of unusual events, the cause of which turns out to be an avatar of Nyarlathotep. They find some notes left by a professor with experience in the mythos that came to the place before them and was killed. The notes contain instructions on how to perform a ritual to summon the Great Old One Cthugha, so that the two beings (who apparently don't like each other) will fight, resulting in both being banished. The notes also suggest that as soon as the ritual is complete, everybody should get at least several miles away from the site.
In Harry Potter And The Order Of The Phoenix, Hermione Granger does this by bringing Dolores Umbridge into part of the Forbidden Forest where the centaurs live. She hopes to trigger Umbridge's hatred of "half-breeds", which will enrage the centaurs and get them to take care of Umbridge for her. It sortof works.
When the centaurs are about to turn on Harry and Hermione, Grawp appears, looking for Hagrid, and gets into a fight with the centaurs, allowing Harry and Hermione to escape.
In Stanislaw Lem's The Tale of the Computer That Fought a Dragon, a robot king accidentally makes a robot dragon; he gets his battle computer to get rid of it—which, of course, it does by making larger and larger robot dragons. Eventually the computer tries to turn itself into an electrosaur and rule the planet, but the king hits it with his slippers and it accidentally turns itself into electrosauce. So Yeah.
In Welkin Weasels: Gaslight Geezers, Maudlin accidentally acquires a magical ocarina which summons a demon if played and can't be thrown away or destroyed, but can only be passed on to another owner. Naturally, he decides to simply not play it. However, he and Scruff are later attacked by the dreaded manless horsehead (the ghostly head of a riderless horse) and use the ocarina to summon the demon to fight it while they run. Later, when they're captured and enslaved at an ironworks, Scruff manages to trick the overseer into taking and playing the ocarina, summoning the demon, which eats the guards (who are mink, and therefore larger and better prey than the weasel slaves, who escape).
Druid: Being hunted by a gigantic cyborg spider? Drop it down a pit. Right on top of the even bigger and grumpier Eldritch Abomination.
Talismans: Being attacked by several smaller, but still huge and tough, magical cyborg spiders? Lure them into the Mist Marsh, where they can piss off the huger and tougher tentacled horrors within.
In the Wizard of Rondo, after the protagonists have learned that Eldritch Abomination the Strix is really the Blue Queen, Tye summons the real Strix. It is not amused.
One of the Silver John stories has a warlock trying to control John by using Sympathetic Magic on a picture of him. John tries to distract him with a silver quarter, but it lands in the center of the spell. The end result is that the spell summons the embodiment of the heroic myth of George Washington (it locked onto the face on the coin), which instantly figures out the warlock's a bastard and beats him into the dirt before leaving.
In the Star Trek novel ''Immortal Coil'', the Enterprise and a space station owned by the immortal Flint come under attack by rogue androids after a sophisticated prototype android (long story...). Luckily for Picard and company, Flint has spent the last century or so collecting other artificial life-forms and AIs, including Richard Daystrom's M-5 computer. Data plugs the M-5 into the station's weapons array, and turns it loose to engage in its primary objective - survival. It mops the floor with the android fleet.
McAdams: You do know M-5 is kinda crazy, right?
Data: 'Crazy' is an imprecise term. 'Single-minded' would be more accurate.
A fantasy novel set in modern times had one of its plotlines deal with the efforts to stop the demoness Lamashtu (as noted under Mythology below) after she was summoned to Earth by a self-deluded worshiper by summoning up her nemesis Pazuzu, in hopes his hatred of her would see them both leaving earth as the one chased after the other (it succeeds, naturally).
Midnight Never Come has the protagonists deal with the dark faerie version of Queen Elizabeth by summoning the Wild Hunt, actually the faerie kings of England that Invidiana had displaced. It's something of a distraction for the Plan A, but it's a big enough threat that she has to go meet it.
Live-Action TV
Primeval has what has to be one of the most epic uses of this trope: Lester is chased by a future predator. He can't defeat it, so he manages to make his way back to the main room of the ARC and tells Leek, who's commanding it, that since he won't beg for his life, Leek may as well just kill him now. Unknown to Leek, Lester opened the door to the cage holding a giant freaking mammoth. Said mammoth does not like the future predator. Said mammothkills the future predator with extreme prejudice.
Played by the villain Crustaceans in the final episodes of Big Bad Beetleborgs. In response to the Beetleborgs finally acquiring the giant Roboborg, the Crustaceans respond by creating the equally giant Boron.
Babylon 5: When the Vorlons aim to destroy a planet with a population of six billion, Captain Sheridan, who knows too well that his fleet cannot take them on and win due to severe firepower and technological disadvantages, summons a fleet of ships belonging to the other "First Ones", who then proceed to destroy the Vorlon planet killer.
In the Season 7 Supernatural premiere, the Winchesters and Bobby summon Death to deal with God!Castiel. Subverted, though, in that Cas merely snaps Death free of their binding spell, defusing the situation. The potential danger of doing this is beautifully lampshaded by Crowley:
You really believe you can handle that kind of horsepower? You're delusional! They'll both mash us like peas.
On one Saturday Night Live sketch Ben Stiller and Tim Meadows play small-town politicians in a series of dueling campaign ads on the topic of "the bat problem," (bat attacks on the citizenry.) The competing candidates advocate such solutions as soldier monkeys, erupting a volcano under the bat cave, and getting larger and more aggressive bats to eat the bats.
The Second Doctor finds himself forced to summon the Time Lords at the end of "The War Games", since he's incapably of solving everything on his own. They appear, sort everything out without much fuss... and execute him for being a renegade with a stolen TARDIS.
In "Ghost Light", the Seventh Doctor tries this and gets in really bad trouble. The enemy at this point is a Human Alien with some hypnotised human minions. The Doctor unleashes a mad angel.
An inversion occurs in Star Trek: Voyager when the Borg ask for Janeway's help in eliminating Species 8472.
Music
The children's song "The Old Woman Who Swallowed a Fly", wherein the woman in question keeps swallowing bigger and bigger animals to catch the one she swallowed before. Ultimately, she swallows a horse. She dies, of course.
Multi-media
Kongu did this in BIONICLE, during the Pit story. He used his Mask of Summoning to summon a giant Eldritch Abomination-style Rahi to kill a 300-foot Matoran-eating Eel. It was an interesting battle. This is pretty much Kongu's mask power, to summon monsters ... the only problem is he doesn't get to control the monster ... nor can he choose what monster arrives.
And this ends up biting him and the other Toa in the ass later on, as the Rahi and the Eel team up with each other and the mutated Gadunka during the Męlée ŕ Trois at the end of that arc.
Mythology
In Assyrian and Babylonian mythology Pazuzu was a Chaotic Evil wind demon who brought drought and storms. However, pregnant mothers often invoked him with amulets to ward off his enemy and, in some versions, wife, Lamashtu, who killed children in childbirth and kidnapped newborns.
Some argue that this is The Artifact of Set previously being a positive chaotic figure embodying destruction and renewal like that of a desert storm.
One Indian folktale was about a king whose palace was constantly infested by mice. The king then orders his servants to send in cats to get rid of the mice, but then the king gets fed up with the cats, and first tries to get rid of the cats with dogs, then tigers, and finally an elephant. When the king becomes annoyed with the elephant, the servants get rid of it with yes, a mouse.
In Fox Trot, Paige is writing a fairy tale where she is a self-insert. Her character comes across a trapped troll that suspiciously looks like Jason, and is faced with the choice of freeing it or hoping a boar would come along and eat it. The last panel is Paige asking if they make "boar whistles" that work, presumably, like dog whistles.
Tabletop Games
Pretty much what the whole Summoner type of wizard is about in Dungeons & Dragons; note that as such wizards become more powerful, the category "monster" may include summoning intelligent creatures from other planes of existence, such as dragons, angels, demons and genie. A necromancer on the other hand may summon various types of undead to deal with whatever troubles him. The druid can summon giant animals, elemental spirits and dinosaurs to do his bidding.
As most creatures a summoner can summon are only about half as strong as the caster at best, this is more of a case of summoning a swarm of smaller fish.
Until he learns Gate (one of the most powerful spells in the core game), which allows the summoning of monsters considerably stronger than the ones the players would expect to fight.
An interesting case is summoning a Bebilith. It's a demon who is best summarized as "a demon who hunts and kills smaller demons". There is even one specific spell which summons an uncontrolled Bebilith that will attack whatever is next to him, but will go for other demons first at all times.
Thankfully a summoned creature can not summon more creature. However, there is a slightly different form of summoning called "calling", and called creatures can call more creatures as powerful as themselves with the notorious gate spell. A rules exploit commonly called "chain gating".
In First Edition AD&D Pit Fiends were powerful lower-plane monsters (Devils) who among their many abilities included the use of the Gate spell at will, including being able to summon other Pit Fiends with it, with no specific limitations.
A similar version of this could happen in older versions of Warhammer and Warhammer40000, as the old Realms of Chaos books (Slaves to Darkness and Lost and the Damned) included rules for releasing daemons bound intoweapons. The daemon released would be a bog-standard example of the type, with the standard equipment. It was possible to get a daemon weapon containing a Bloodthirster of Khorne, whose standard equipment at the time included... an axe containing a Bloodthirster of Khorne. In terms of balanced points battles, it was a game-breaker, with the number of Greater Daemons you fielded (in addition to your army) limited only by the number of turns you were playing, and the number of Bloodthirster models you owned...
This currently possible again in the Storm of Magic expansion with scrolls of binding that allow you call in any monster from the earlier rulebooks, including greater daemons, as well some monsters created for the expansion. These monsters are "biggest fish" available, including stronger version of the greater daemons, a supersized giant, a giant mammoth, and super versions of the dragons, some of which can be made lord level wizards. This is more balanced than old means of bringing out bound daemons since the controlling player has to pay for the monsters in point cost like they do everything else.
A variation of this trope occurs in the Warhammer40000 background: with Hive Fleet Leviathan rapidly closing in, the higher-ups of the Imperium decided to divert the swarm into an Ork-held star system as a last-ditch delaying effort. As of the current fluff, they're still going at it, but Imperial generals (rightly) fear that whoever wins will have become much stronger, and will be coming after them next...
Call Of Cthulhu supplement Terror From The Stars. The "Field Manual of the Theron Marks Society" says that when facing extremely powerful monsters, "The only hope in this situation is to summon another deity or monster with a natural hatred for whatever it is that is attacking."
The Jurassic Park card game allowed you to summon a Tyrannosaur to scare off the smaller predators, the venom-spitting Dilophosaurs and pack-hunting Velociraptors. Or even another Tyrannosaur. But then you would have to fight off the T-Rex as well, after it scared the others off.
To further elaborate: most Goblin Contracts have some kind of drawback to go with their main effect. In the case of Call the Hunt, the main effect is that drawback.
Mutants And Masterminds has a summoning power. A drawback you can take for it makes everything you summon hostile toward you. You might summon a bigger fish to deal with your foes, only to have to summon another when the first turns on you.
In the storyline of the Deadlands CCG Doomtown, the Big Bad was eventually defeated by waking up the manitou who brought Abraham Lincoln back as one of the Harrowed. Lincoln's willpower had long since beaten it down, but shooting him with an enchanted gun firing the same bullet that killed him before finally pissed it off enough to rise again.
Happened in the BattleTech Expanded Universe. The mercenary Northwind Highlanders are contracted to raid a world held by Clan Smoke Jaguar, perhaps the most brutal and bloodthirsty of the Clans. Instead of the inferior second-line opponents they were told they'd be facing, their DropShips are shot down by an entire front-line force of Jaguars. The Guile Hero protagonist's plan is to masquerade as Jaguars and go besmirch the honor of the Nova Cats, a clan of mystical but no less impressive warriors, to attack and destroy the Jaguars on the planet and free the trapped Highlanders. It works stunningly, as the Highlanders escape and all the Jaguars are destroyed.
You can also summon an Arapaima if you literally just want a bigger fish.
Also Cthulhu vs. Satan. Cthulhu wins.
Additionally "God vs. Vampire". Vampire wins.
And "God vs. Death" Death wins.
This trope constitutes much of the gameplay in the final level of Eternal Darkness. Naturally this leaves one of the Eldritch Abominations wandering around unopposed, so the ghost of Alex's grandfather has to subsequently bind the Bigger Fish.
Grim Grimoire has this as well in the infamous battle. After Lillet steals the Lemegeton and releases Calvaros, she gets right to work summoning Grimlet to erase him — as you learn, the two had a deal, but Grimlet was sealed away before he could collect his "fee". After holding off the worst from Calvaros for thirty minutes, Grimlet appears, takes Calvaros' soul... and then gets owned by Lillet herself shortly therafter. What a bitch...
Doom II has a special level just for this purpose. In it, you are presented with both a Cyberdemon and a Spider Mastermind, the two most powerful monsters in the entire game, at the same time. The only way you will survive this is if you provoke one into firing on the other, then take out the survivor.
That's just the easy way to kill them. For the same reason you are able to singlehandedly defeat either of them, however, you are also perfectly capable of defeating both. You just need more ammo.
There's also an earlier non-secret level in Doom II which features a room with at least twenty Barons of Hell and a single Cyberdemon. Due to the way they are positioned, the Cyberdemon will immediately shoot at you as soon as you open the door, but since the Hell Knights are standing in the way, they'll get hit and turn on the Cyberdemon. It's very likely the Cyberdemon will win this fight, but by the time he does, he's so weakened that it won't take much to kill him.
In the original Doom, there was a secret level with this premise. In the room you start with there are half a dozen Barons of Hell. In the next room are a dozen Cacodemons. The best survival strategy involves running from room to room, allowing the monsters to mix and get caught in each other's crossfire, which will make them turn on each other as long as you aren't fool enough to draw their attention.
In the Grand Finale of (the main questline of) The Elder Scrolls IV Oblivion, Martin Septim summons the Freaking Dragon God of Time, Akatosh, to fight off Mehrunes Dagon, who enters the Imperial City in the flesh.
A popular way to train weak pokemon is to let them face more powerful mons and then switch to a even more powerful creature who can defeat the enemy, your two pokemon then share the experience equally between them, except in the 5th Generation games, where the weaker Pokémon will always get the lion's share of the Exp.
The Elder Scrolls V Skyrim gives you scrolls that can summon animals to your aid, spells that can summon atronachs (embodiments of the elements) or a Dremora Lord to fight for you, and a shout that can summon a dragon, Odahviing when far along in the main quest.
Whenever the Dragonborn is sent to deal with one of the Dragons that's taken roost near cities.
Early in Iji the plan with dealing with the Tasen is to alert their much more powerful enemies about their presence. They're worse.
In Dragon Quest VI, about halfway through the game a kingdom summons a legendary demon in the hopes that it will kill their world's Crystal Dragon Satan for them. Normally, what happens is the demon is too powerful to control and ends up destroying the kingdom for their arrogance. However, if you have an insanely overpowered party (we're talking months of grinding or the use of a gameshark here), you can beat the demon in combat and gain its respect, resulting in a funny bonus ending in which the demon flies over to the final boss and curbstomps him for you.
Said demon, Nokturnus, can be created for your party in one Dragon Quest Monsters to invoke this trope once again. DQM: Battle Road Victory lets you sic various Final Boss monsters and more for similar results.
Whenever Super Robot Wars include Neon Genesis Evangelion, a strategy that can be useful against powerful enemies is to let EVA01 be destroyed. Instead of getting removed from the tactical map, it will go berserk, gain massive stat boosts, and will destroy most enemies with ease. However, it's uncontrollable and might attack your units instead (and you still need to pay its 40000 repair cost.)
In Super Robot Wars Alpha however, the use of a special item called Tem Ray's Circut can cheeze this, setting the Repair cost to a measly 10 Credits... while taking a hit on other stats.
The Metroid species have this as their entire purpose. When the X Parasites were discovered to be insanely destructive and dangerous, the Chozo genetically engineered the perfect predator to get rid of them. Decades later, when Samus kills all the Metroid species, the X parasites' population explodes.
Bayonetta slays all bosses (and many of the larger, normal mooks) by summoning greater and greater demons. This includes the final boss, Jubileus. Always a bigger fish, indeed. And she does it with her hair.
Also in the battle against Father Balder she summons several demons of growing strength in a sort of summoning style Worf Effect.
BioShock 2 has Summon Eleanor Lamb (in a big sister suit) as a plasmid.
In the final battle of Bioshock Infinite, you gain the ability to control Songbird and can command it to attack the various airships coming in or certain areas that enemies are likely to be grouped up in.
Mass Effect 3: At one point, all the heavy artillery is destroyed before a Reaper can get blasted with it, and the heroes appear out of options for dealing with said Reaper. They use the Maw Hammers at the Krogan proving grounds to summon Kalros, the "mother of all Thresher Maws", who is very angry that a Reaper is intruding on its territory...
Note that they were doing this just to distract the Reaper. They didn't count on the Thresher Maw to actually kill it!
Throughout the whole series, rule of thumb seems to be that if there's a problem, send Shepard to deal with it.
This trope is in used full-force with the Leviathan DLC, which reveals that the Leviathan entity is what killed the Leviathan of Dis Reaper. And you see a Leviathan kill a Sovereign-class Reaper firsthand!
The titular rifts of, well, Rift can sometimes be triggered by specific actions. Since all six of the elemental planes hate each other, this can be a quick way to get out of a hairy situation.
In Dead Space 2, Isaac has to get past a government security force with orders to shoot him on sight. How does he do it? By powering down the lights and door locks, leading to a massive army of necromorphs slaughtering their way through the government forces.
In Guild Wars Prophecies, after fighting your way through the fortress of the Mursaat, who were conquering the entire continent at that time, you (unknowingly) release the Titans which come under the control of the Lich Lord, who has been manipulating the Players for some time by then. You have to kill the Titans too of course.
In Baldur's Gate 2: Shadows of Amn, a powerful wizard can summon various massive demons like Cacofiends and Pit Fiends to face whatever the enemy is. But unless you cast Protection from Evil on your party, it will then go after you.
In Freedom Force vs The Third Reich you summon your greatest enemy, the Time Master, an insane supervillain with complete control over time and space to fight Entropy, an insane supervillain who grows more powerful as things become more chaotic while she's in the process of ripping the universe apart.
The 'Summon Baatezu' ability given to Hellfire Warlocks in Neverwinter Nights 2 works like this. A powerful Devil will fight by your side for a number of rounds, but if you keep it around too long, it might turn on you...
Played with in In Famous, the reason the ray sphere was made was because Kessler needed to make Cole strong enough to be able to stop the Beast, which Kessler himself had already failed to beat, therefore he went back in time to power his former self up until he became a "bigger fish". Zig Zagged Trope. indeed
That's not even the end of it. In inFamous 2, it's revealed that during the events of the first game, one of the helpful NPCs was accidentally turned into the fish that Cole was supposed to be bigger than, before he had a chance to become bigger than it!
Subverted, and then paired with Nice Job Breaking It Villain, in Tales of Phantasia. Dhaos needs a Mana Seed to revive his dying homeworld but the only way he can get it is from the World Tree; which humans are bleeding dry through their use of Magitek. So he sends (what he thinks) is an even stronger army of monsters out to smash their weaponry, resulting in the biggest conflict in the world's history. However, not only do his efforts completely fail (because the humans have the Five-Man Band on their side), but it's implied that the war he kickstarted led to the version of the present where Mana is all but gone; making it impossible for him to fulfil his goal anyway.
An antagonistic, but not evil, example occurs for the final battle of The Lost Age, wherein the heroes are the "Big Fish". So, what Bigger Fish does the Wise One summon to stop them? Why, a three-headed dragon made from their parents, of course! The heroes win, obviously, but the intention was still there.
Part of Golden Sun Dark Dawn revolves around you hunting down and activating the biggest BFG in Weyard's history so it can be used to destroy the Grave Eclipse; which has blanketed half the world in darkness, from which Demonic Spiders are appearing to kill everything.
In the ending of the normal path in Soul Nomad & the World Eaters, the heroes face the finalboss, three Physical Godsmerged into a single monster.After initially beating it, said villain devours the souls of a bunch of its followers and creates two clones of itself. With no other options, the main character Revya gives Gig, a Physical God who was also living inside him/her, full control the body, while Gig assuring that they'd both still be alive after he gave up control to convince Danatte to agree. Gig easily kills all three monsters, but dies since not taking control of Revya left him without a body, but Heaphness revives him in the ending anyways.
In Monster Hunter Tri, A relatively low-level monster known as the Qurupeco has the ability to mimic the calls of other monsters and summon them to its aid. In higher-level hunts, this usually involves monsters much nastier than it is.
If they have hunters of lower ranks, sometimes a group will intentionally try and make the Qurupeco summon said bigger fish.
In Dragon Age II, it's implied that one of the reasons Knight-Commander Meredith lets Mage!Hawke roam free is because she recognises that someone who single-handedly managed to curb-stomp the Arishok is not to be trifled with and would be better used as a weapon to turn against Kirkwall's enemies.
Nukees Gav, when in the after life and faced with a giant snake, decides to summon the god of alcohol, who has sworn to kill Gav.
After Bun-Bun first shows up in Sluggy Freelance Torg and Riff try to get rid of him by hiring a grizzly bear to be the new Team Pet, on the condition that he gets rid of Bun-Bun first. Turns out grizzly bear < mini lop.
When Mike of College Roomies from Hell!!! gets attacked by a large octopus, he realizes the small knife he has won't be enough to win the battle so he cuts himself, attracting a shark with the smell of his blood to attack the octopus for him.
This happens in It's Walky! when SEMME is attacked by the Britjas (British ninjas; don't ask). After getting fought to a stalemate, they use the Power Booster Rod (a tree branch containing absurd amounts of extradimensional energy; again, don't ask) to summon The Wanderer, a being with god-like power who is very interested in keeping dimensional travelers out of his dimension. The Britjas are travelers from another dimension. Guess what happens.
Done as Parody in Nodwick, the heroes are going to make a barbeque for the locals so they go out hunting. The first thing they catch is a rabbit, which they use as bait to start climbing the food chain until they catch a tarrasque, one of the biggest and most fearsome (and also most foul smelling) animals in the world.
Done to some interesting effect an early Apple Valley. In an attempt to counter a giant rampaging Apple of Chaos (evil cousin to The Apple of Discord), Doctor Hubris uses a magic wish to summon Gayzilla from a sister comic by the same author. A careful read-through of the archives shows that Gayzilla did *not* exist as part of the Apple Valley continuity beforehand, but has ever since.
What do you say to an angry god to keep from getting killed? If you're a character in User Friendly, the answer is "HasturHastur Hastur."
Web Originals
In Kickassia, the resistance invoke this trope onto Spoony, convincing him to give into the Dr. Insano inside him to combat the Nostalgia Critic.
Note that Linkara thought it was a stupid plan and asked if Angry Joe was high when he planned it. Also, it didn't work and indirectly caused Santa Christ's death.
Western Animation
In the "Super Best Friends" episode of South Park David Blaine has brought the giant stone statue of Abraham Lincoln to life and it is terrorizing Washington DC. The SBFs solution: build a giant stone statue of John Wilkes Booth, which sneaks up behind the Lincoln statue and shoots it in the back of the head.
In the first segement of Futurama: "Anthology of Interest I", a 500-foot Bender is attacking New New York City. According to Prof. Farnstworth, the only thing that could stop him would be "an even more equally big monster", and so he uses his growth ray on Zoidberg to battle him.
In the Grand Finale of Jackie Chan Adventures, Shendu is freed to combat his son Drago, who had absorbed the powers of all of Shendu's siblings. While they are battling, Uncle sends them both into another dimension.
There were a few occasions where The Real Ghostbusters had to let the Stay Puft Marshmallow Man out of the containment unit to fight another huge ghost hand-to-hand while they figured out how to put it down for good.
The Venture Brothers' Brock Samson engineered a situation like this when he and the Ventures were simultaneously hounded by the OSI and the Monarch, pitting the two against each other as a double use of the trope.
Jerry from Tom And Jerry sometimes sought protection from Tom in Spike the bulldog. Odd, since in Real Life dogs also kill mice and rats, sometimes just for fun.
One of the great moments in Robot Chicken: The Peanuts gang have almost all been killed off by The Great Pumpkin, and Charlie Brown, fleeing for his life, cowers at the base of the tree. The Great Pumpkin notices all the half-eaten kites and has time for an Oh Crap before this Crowning Moment of Awesome:
In the episode "The Shrieking Madness" of Scooby Doo Mystery Incorporated, Scooby and the gang face Char Gar Gothakon, The Terror that Hath No Name, a creation of H.P. Hatecraft. In the course of defeating the Cthulhu stand-in, they get assistance from Harlan Ellison. Seriously. (This was easily the weirdest Scooby doo episode ever.)
From an episode of Ben 10 Ultimate Alien. After getting it handed to her pretty well by her crazy, full anodite cousin Sunny, Gwen admits she can't beat her. And promptly calls her other full anodite relative, her Grandma Verdona, who easily puts Sunny in her place.
Done in the original series too, during Secret of the Omnitrix. When Vilgax and his giant robots are set to annihilate Ben and his friends, Azmuth unlocks Way Big, Ben's strongest alien form, a giant who throws Vilgax into space like a softball.
The Simpsons did this 4 times in a row: in one episode Bart accidentally kills a bird and nurses her eggs out of guilt. When the eggs hatch, they turn out to be of a voracious species of lizard that eats birds and leaves eggs in their nests. Bart releases them and Skinner tells him he has no idea what he has unleashed ...and later is commended for it because the lizards wiped out the pigeon population, which the town considered a plague.
Skinner: Well, I was wrong. The lizards are a godsend.
Lisa: But isn't that a bit short-sighted? What happens when we're overrun by lizards?
Skinner: No problem. We simply unleash wave after wave of Chinese needle snakes. They'll wipe out the lizards.
Lisa: But aren't the snakes even worse?
Skinner: Yes, but we're prepared for that. We've lined up a fabulous type of gorilla that thrives on snake meat.
Lisa: But then we're stuck with gorillas!
Skinner: No, that's the beautiful part. When wintertime rolls around, the gorillas simply freeze to death.
An episode of Courage the Cowardly Dog has Eustace turn into the Monster of the Week; a kangaroo monster, which was known for jumping onto things to death (and is extinct as the dinosaurs). As he's jumping all over the world with Muriel hostage, Courage's computer tells him that "the only thing that can stop a kangaroo monster, is ANOTHER kangaroo monster". Reluctantly, Courage undergoes the same transformation Eustace did (kangaroo monster bone transplant) and proceeds to fight him in Paris, France.
The American Dad episode "Bully for Steve" has Stan act as Steve's bully in an attempt to toughen him up. Steve, after getting fed up with his dad, contacts Stan's former bully, Stelio Kantos, who proceeds to beat his dad up.
Real Life
Has happened a few times with invasive species. An example is in Australia, where rabbits had become a serious problem, so foxes were imported to try to kill the rabbits. As often with this trope, the foxes became a problem in themselves, while having little effect on the rabbits.
While we're on the subject of rabbits, it's theorized that the reason they scream bloody murder when seized by a predator is because it just might invoke this trope, causing a rival predator to intervene and giving the rabbit a slim chance to get away or at very least make predators to scared to hunt the rabbits.
When eaten by a turtle, the Portuguese man-of-war releases a shark-attracting chemical.
Some deep-sea jellyfish light up when being eaten by fish as so they will attract bigger fish or squid to eat the other fish.
Can often happen in geopolitical situations as well. See, for example, the U.S. supporting mujaheddin in Afghanistan.
A reason a great many people in many nations supported Nazi Germany was because they wanted to build it up to oppose the U.S.S.R.
The best example that comes to mind if Finland. The Soviets were looking over the border and remembering the White Terror, and soon enough invaded. The Finns put up a good fight, ironically their performance was caused largely by the Soviets, and then signed up with the Nazis who the USSR was just not ready to deal with quite yet. A bigger fish indeed.
Then they subverted it when they were forced to kick out the Germans due to the cease-fire agreement with the USSR.
It also applies later in World War II when the Nazis showed their true colors and the US and Britain backed Stalin against Hitler.
Go to the Real Life section of Godzilla Threshold for a nice writeup of all the bigger fishes summoned by a number of countries throughout a large chunk of history.
The Aztec and Incan empires were so brutal to the people they ruled that many of the lesser Indian nations were more than willing to join the conquistadores in conquering those empires.
Related: in the American West, many Indian tribes would use an alliance with the white man to gain leverage over their enemies.
A very popular video shows some lions attacking a cape buffalo calf near a watering hole. The struggles of the calf in the water attract a crocodile, which tries to fight the lions for their prey and gives the calf a chance to escape. However, the crocodile loses and the lions are about to set upon the calf. Then the entire cape buffalo herd masses on them...
When Kuwait was invaded by Iraq and completely overwhelmed, it resorted to asking the United States to push Iraq out knowing America had interests in it. This mostly worked as intended, with America and its coalition allies beating Iraq easily despite initial fears, though Iraq getting desperate during the coalition air campaign pummeling for weeks sadly resulted in them dumping a large amount of Kuwait's oil into the sea and setting its oil wells on fire in a desperate attempt to force the coalition to attack.
Troops in Afghanistan fighting the Taliban invoke this trope with a side of Death from Above in the shape of the Apache attack helicopter.
In the Korean War South Korea was getting steamrolled by North Korea, when they called the UN for help more than a dozen nations come in to their help and turned the tables on the North, then the USSR and China had to come in and help North Korea.
The "King Cotton" doctrine was the South's attempt to invoke this trope during The American Civil War. In essence, they figured that British and French industry were so dependent on Southern cotton that they would come to the Confederacy's rescue and secure its independence. However, the Union understood this, threatening Britain with war if it started to aid the South, practicing assiduous diplomacy to persuade Europe to keep out of the conflict, and tailoring rhetoric and policy decisions—such as the Emancipation Proclamation—to win British and French public opinion to the Union side. It worked—Britain and France stayed out.
