The Apocalypse Stone

The Apocalypse Stone is an Advanced Dungeons & Dragons adventure module published by Wizards of the Coast and credited to Jason Carl and Chris Pramas as authors. It's designed to give an epic adventure for high-level characters that will end with the destruction of the game world.

When the gods created the world, its seed was the stone known as The Stone of Corbinet. Once the world was complete, they sought a worthy champion to guard the Stone, and settled on a man named Pescheour, whose family has guarded the it in their castle ever since. Now, however, an evil prince of the family, Garloth, has sworn revenge after being denied kingship. Not knowing the Stone's true importance, he plans to steal it. To this end, he feeds the player characters false information about a test of heroes. Once they have retrieved the Stone, Garloth retires with it in his own castle, not knowing that its removal from its proper place is cutting the world off from other planes of existence and will eventually cause its destruction. After the heroes find this terrible truth, they are sent on a last final mission to set things right again.

Though the adventure isn't terribly significant in its own right, it's got some good examples of tropes in it.

Tropes used in The Apocalypse Stone include:

Batman Gambit: Garloth's elaborate plan to get the heroes to look for the castle and the Stone by pretending it's a divine test for heroes.
Big Bad: Prince Garloth. It really is all his fault.
Black Knight: Lucius, being a Death Knight.
Character Alignment: Well, it is a D&D module...
- Chaotic Evil
  - Prince Garloth. He's willing to do anything for the sake of nothing more than his own pride.
- Lawful Evil
  - Moloch. As an archdevil, pretty much literally an Anthropomorphic Personification of it.
  - Lucius. A Death Knight seeking redemption.
  - Etana, the devil-worshipping witch.
- Lawful Neutral
  - Fetch. Works for the Big Bad, but rather than evil is simply not smart enough to question orders of any sort.
  - Lucius on his way to redemption.
- Lawful Good
  - The generic "God of Justice", almost certainly.
Complete Monster: Moloch used to be an archdevil, so it was pretty much part of his job description. And then the player characters went and pissed him off...
- Garloth seems objectively bad enough to qualify, but he's not given the necessary buildup.
Cosmic Keystone: The Stone of Corbinet.
Demon Lords and Archdevils: Moloch is an archdevil in exile. And just when he was about to conquer his layer of Hell back, someone cut off his hiding place's connection to other planes.
Downer Ending: The default one (duh).
Earthshattering Kaboom: Specifically, "the world swirls away into the cosmic dust from which it was created."
Evil Prince: Garloth Pescheour.
Evil Sorcerer: Garloth.
From a Single Cell: This property of the Tarrasque is exploited in the secret test of foresight given to the player characters. Don't swear to kill any unspecified giant monsters when you're supposed to be saving the world. It might be harder than you think.
Kaiju: With the world going to end anyway, the legendary Tarrasque comes out to destroy at least a few villages while it still can.
MacGuffin Delivery Service: Garloth has sworn a magical oath not to remove the Stone from the castle, but it doesn't say anything about getting others to do it...
Mind Rape: Garloth's driving his brother the king insane.
Nice Job Breaking It, Hero: And how.
Only the Worthy May Pass: The rules about finding Castle Perscheour involve a test of character. When the characters have to find it a second time, the avatar of the God of Justice, bound by the rules, has to arrange them a series of tests too.
Revenge
- Garloth was the elder son of the king, but sensing that he was a bit selfish, his father gave the crown to his brother Alain instead. Secretly seething with fury, Garloth turned to the study of very dark magic, until his brother told him to stop it. Garloth stormed out, but later came back, seemingly willing to reconcile but really just in order to drive his brother insane, transform the rest of his family into monsters, and get someone to steal the Stone for him. Um, hate to tell it to you, but your father may have had a point.
- That's nothing, though. Moloch had planned his re-conquest of his former realm in Hell a long time, only to be foiled at the critical moment because he couldn't leave the world he was hiding on. When he finds out the player characters are to blame for severing the world from the planes, he gets... angry. He starts out by feeding the player characters human-meat buns in an inn disguised to look pleasant but in reality containing a bloody slaughter, and continues by killing their loved ones and sewing these into grotesque golems that they have to fight. To finish them off, he attacks them in the funeral, inflicting as much collateral damage as possible and readily explaining that they have doomed their world.
World Ends, Everyone Dies
Suicidal Cosmic Temper Tantrum: It's not that Garloth plans to destroy the world, and he's hopelessly trying to save his own skin to the last - but he will never consider doing it the obvious way by taking the Stone back. "If he can't be king, then the whole world can burn."
Unwitting Pawn
Using You All Along