Straight: Exactly every ten thousand years, all civilizations on Planet Troperia is wiped out by an unknown factor.
Exaggerated: Exactly every hundred million years, all life in the Universe is wiped out by an unknown factor.
Downplayed: Exactly every ten thousand years, all civilizations on Planet Troperia is set back by a major disaster or cataclysm. The people know this well and are prepared for it.
The Will of The Planet wipes out civilizations before they become too advanced and start draining all the Mana on the planet.
Planet Troperia is subject to a regular cycle of natural phenomena caused by its peculiar astronomical or geological circumstances, which its inhabitants can't quite explain, and which periodically invokes a cataclysm.
Subverted: The Will of The Planet decide to halt the apocalypse this time, due to a pure-hearted maiden travelling to The Lifestream and convince the Planet that all people are good. Reading her memory, the Planet know this to be true.
Double Subverted: Some greedy jackass decide to exploit Mana anyway, and the people suffer the Planet's final solution due to their action.
Parodied: "Right, the world ending happens every year. Does anyone have anything they reserved for tomorrow?"
Zig Zagged: ???
Exploited: An Omnicidal Maniac speed up the process of Mana exploitation to speed up the coming of the apocalypse to the world that he hates.
Defied: Some people level themselves up to stand the world-ending force face to face. If they succeed, there is a serious risk of the death of the Planet itself.