Ravenloft a.k.a the Land of the Mists a.k.a. the Demiplane of Dread is the collective name for a group of domains of varying sizes and populations which float in the mists of the Shadowfell. The domains are ruled over by the Dark Powers, unknowable and omnipotent beings who imprison and torment the Multiverse's most vile evil-doers. Each domain is ruled by a Dark Lord, a powerful villain who is at once the master of their domain and a prisoner within it. The domains are separated by the mists, but certain individuals called mist walkers can travel through the mists at will from one domain to another. The mists are also used by the Dark Powers to draw in mortals from other planes of existence into the Demiplane of Dread. Ravenloft is a self-contained universe. No one can get in or out without the Dark Powers permission, including the gods themselves.