The Mists are the unexplainable, unpredictable, and unfightable planar vortex weaponized by various Dark Powers to entice killers and other evil victims into becoming Dark Lords and masters of dread.
About
The mists resides in their own demiplane, isolated from all other planes, including the Material Plane. No spell-not even wish-allows one to escape from the domain. Astral projection, teleport, plane shift, and similar spells cast for the purpose of leaving he mists simply fail, as do effects that banish a creature to another plane of existence. For the purpose of spells whose effects change across or are blocked by planar boundaries (such as sending), the mists are considered its own plane. Magic that summons creatures or objects from other planes functions normally within the mists, as does magic that involves an extradimensional space.
While in the mists, characters who receive spells from deities or otherworldly patrons continue to do so. In addition, spells that allow contact with beings from other planes function normally-with one proviso: the Dark Powers can sense when someone in his domain is casting such a spell and can choose to make themselves the spell's recipient instead.
Escape
Though there is no easy way to escape the mists, it is possible to be pulled out of them by an extraordinary power on the outside. Cultists of Nerull knew of a ritual that pulled people back to the material plane after they had been swallowed, but it had to be performed from the Material Plane by friends or associates of the swallowed individual.
