Anchorite Vaults

The Anchorite Vaults of Tempa were a dungeon in which a number of mages were imprisoned, locked in when their goddess was destroyed, turning their term of service as anchorites into a perpetual hell of isolation guarded by clay golems and elementals that roam the halls, all overseen by a beholder called The Gatekeeper. It features the room of the mad rectoress as well, who was warped like the other mages into a hideous mindflayer-like creature, and the final vault is guarded by a chained celestial. Various keys throughout open various doors, and traps abound for the careless (especially the entry trap, which requires a party member stay behind to operate the door mechanisms, trapping themselves in a pool of magic-sapping slime, soon to drown unless the party can defeat or negotiate with the Gatekeeper).