Alice is a Sealed Evil in a Can. Bob, either because he was promised something like immortality or riches, thinks he can control her, or because he thinks Alice isn't as evil as everyone says she is, tries to free her. After a bit of hard work, and possibly some outmaneuvering of people with more common sense, Bob frees Alice. However, rather than rewarding Bob for his service or even giving him a simple thank you, Alice tosses Bob into her mouth and eats him without a second thought.
This trope when somebody frees or summons a Sealed Evil in a Can, and is immediately eaten or otherwise destroyed by said evil. Often a trope that appears at the climax of a story. A sub-trope of Evil Is Not a Toy and a common fate of cultists summoning an Eldritch Abomination. One of the hazards of calling up what you can't put down. It's also a sub-trope of You Have Outlived Your Usefulness.
- This happens to Samantha the necromancer in episode 3 of Soul Eater when she summons Wrath of the Pharaoh. While she had no issue controlling the mummies before that point, the Pharaoh simply devoured her instead.
- Jaune Arc, Lord of Hunger: In the chapter "Legends", a group of Sith cultists attempt to acquire the Mask of Darth Nihilus in order to reawaken the ancient Sith Lord's spirit. Upon being awoken, one of the first things that Nihilus does is turn on the cultists who summoned him and drain them of all their Life Energy. Justified since Nihilus's soul needs to feed on the Force to survive and had been spending thousands of years trapped in complete isolation within his mask. By the time he woke up, he was starving and instinctively attacked all living things within his vicinity.
- In The Bartimaeus Trilogy, it's generally stated that demons will attempt to eat their summoners if they fail to draw a proper pentagram or stray outside it. Bartimaeus himself alludes to having eaten a few wizards who made silly mistakes in the past. In book two, a wizard is eaten by a demon because he copied the summoning circle from a book whose printer had deliberately drawn it wrong in revenge for the wizard assaulting and crippling his son years earlier in the prologue.
- In The Belgariad and Malloreon by David Eddings, this is a common fate of Demon-summoning sorcerers. The sorcerer can only maintain control of a summoned demon by continuously forcing it into a shape he controls, correcting deviations with more magic. If he gets it wrong, he gets eaten, generally followed shortly by everyone else in the vicinity.
- In The Last Battle, Shift uses the humans' fear of Tash to increase his own wealth and fame. This involves posing as Tash's high priest/chosen one and constantly threatening to sic Tash on Shift's enemies. The real Tash eventually learns about this, and he is not impressed.
Tash: Here I am. What hast thou to say?
- The advice given in The Case of Charles Dexter Ward
I say to you againe, doe not call up Any that you cannot put downe; by the Which I mean, Any that can in Turne call up somewhat against you, whereby your Powerfullest Devices may not be of use. Ask of the Lesser, lest the Greater shall not wish to answer, and shall commande more than you.
- In the Ultramarines novel Nightbringer, the Big Bad of the story, Kasimir de Valtos, stages a civil war to seize control of the planet Pavonis so he can reach and open the tomb of the C'Tan entity known as the Nightbringer, in the belief it will make him immortal as a reward. When he actually succeeds, Kasimir is briefly connected to the Nightbringer's mind through an empathic link, causing Kasimir to go utterly insane with horror at the realization that the Nightbringer is as far removed from him as he is from an ant, and the C'Tan has no reason to even acknowledge his existence, let alone reward him. Kasimir is reduced to tearfully begging the Nightbringer to make him immortal, which only results in the creature deigning to notice him for long enough to kill him.
- In Samurai Sentai Shinkenger/Power Rangers Samurai, Dayu's reward for fully restoring her master is to be immediately absorbed so he gains a human side and thus immunity from the sealing spell that kept him in his can for most of the series.
- In the episode "Die Hand Die Verletzt" of The X-Files, Mulder and Scully investigate a seemingly Satanic-inspired murder in a small town. Turns out the killer is none other than Satan himself, who was summoned by the locals through rituals to advance their careers, and he's pissed because they aren't true believers.
- In Pathfinder, Daemons stand out among Evil-aligned Outsiders as Omnicidal Maniacs that will immediately try to devour their summoners, body and soul, and usually continue to try even if they get roped into a Magically Binding Contract. While Devils will try to ruin their summoners with bargains and Demons encourage For the Evulz-style debasement, Daemons just want all life to end.
- Magic: The Gathering invokes this trope via Feaster of Fools, a Demon that has both Convoke (meaning that your other creatures can help you summon Feaster of Fools) and Devour (meaning Feaster of Fools can eat your other creatures when summoned to get stronger, which most likely will be the same people that Convoked it).
DCI Ruling: "[Feaster of Fools] can devour creatures that convoked it, and those creatures can reflect upon the wisdom of convoking a demon."
- In Dark Cloud, once the Dark Genie is free, it eats the person who organized the ceremony. The creature justifies this by saying that it hadn't eaten in 400 years and was hungry.
- In the finale of Mega Man Battle Network 3: White and Blue, Lord Wily's consciousness (he pulled a Brain Uploading earlier) is consumed by the Psycho Prototype Internet that he awakened and unleashed on NetSociety, Alpha.
- A notorious and memetic example occurs in World of Warcraft with gnome warlock Wilfred Fizzlebang, self-proclaimed Master Summoner, whose botched attempt to summon a doomguard ends up with him unleashing something much more powerful and hammier - the Eredar Lord Jaraxxus. It doesn't end well.
Jaraxxus: TRIFLING GNOME! YOUR ARROGANCE WILL BE YOUR UNDOING!
- On that note, for a while it was possible for a player character warlock to meet this fate when summoning Doomguards and Infernals, as instead of being bound fully to the warlock like their regular pet demons, these two were by default hostile and only controllable via the notoriously unreliable Enslave Demon spell, which had a tendency to break at the worst possible moment, making these demons Awesome, but Impractical for purposes other than griefing in low-level areas. Later expansions made them less impractical.
- Occurs in the in-game book A Tragedy In Black in The Elder Scrolls V: Skyrim, wherein a child uses a spell to summon a Dremora to help him enchant a dress for his mother's birthday. The Dremora offers him a Black Soul Gem (in the Elder Scrolls universe, enchanting is done by trapping and using the souls of other creatures), which the boy accepts. It turns out that accepting a gift from a conjured creature breaks the binding spell that forces it to obey the summoner's will. Fate Worse Than Death of a Child ensues.
- This trope is normally not a concern for Shin Megami Tensei adventurers. However, summoners unable to tame the demons they summon will suffer this fate in Devil Survivor and Harada's idiotic attempt to create a connection to the Abyss to furnish him with limitless demon servants gets botched to his detriment in Shin Megami Tensei II.
- In Cultist Simulator you can perform rituals to summon various monsters which can sometimes go wrong, you can either dismiss the monster at no cost other than the resources you used on the summoning or you can attempt to control it, if you fail to control it it will either attack you, attack your followers, or just slaughter civilians which attracts the authorities to you
- Girl Genius: The monster the Quintillius Harmon and his cultist minions summon makes an attempt to eat him before he ascends and gains control over it.
- Fate/type Redline: In chapter 10, the mediator tells Tsukumo that in the previous Grail War that a Servant killed their summoner after they were summoned and contracted with a new Master.
- A staple of The Unspeakable Vault (of Doom) is Cthulhoo eating cultists that just summoned him.
Cthulhoo: Yum yum!
- In the first season finale of the Brazilian series Historietas Assombradas para Crianças Malcriadas ("scary stories for naughty children"), Pepe tries to summon a Cthullu-esque Eldritch Abomination to end the world as a way to prove to his grandma, who is a witch, he didn't always leave things halfway. As soon as it arrives, however, it immediately eats him and spits his bones out. Fortunately, the episode turns out to be a story Pepe's grandma was telling him at bedtime, exactly to tell him why he should never leave things unfinished.
- What If...? (2021): In the first episode, "What If... Captain Carter Were The First Avenger?", the Red Skull attempts to summon a tentacled Eldritch Abomination to serve as Hydra's champion and execute his megalomaniacal ambitions, only to be promptly crushed by said monstrosity.