The culminating event in the game Nethack, in which your character ascends to demigodhood by sacrificing the Amulet of Yendor on the high altar of your god in the astral plane, after escaping Moloch's Sanctum, Gehennom, and Dungeons of Doom with the Wizard of Yendor popping up trying to steal back the amulet, then passing through the four elemental planes.
Attempting to interfere with your ascension are the three other riders of the apocalpyse (you are soon to become War*), who reincarnate as necessary, various angels, and assorted other nasty monsters.
The equipment you rely upon to help you do this is called an Ascension Kit.
*this correction thanks to JerboaKolinowski
Also, the mechanism in The Kingdom of Loathing by which one starts from the beginning, with new shinies.