Dream vestige

A dream vestige is an intangible entity, more like a huge mass of fog with anguished faces appearing in it, stretching, twisting, and dissolving back into the vapor. It is accompanied by a chorus of faint voices, some moaning, some gibbering, and others laughing. It burns with an insatiable hunger and snatches up living beings with tentacle prodruding from its mass, dissolving them into nothingness. Only mindless undead beings such as zombies, skeletons, and golems can endure its touch.

A dream vestige begins by gathering hundreds of nightmares, combining them, and infusing them with the energies of undeath. It grows by devouring any being possessed of a mind. It can pass back and forth between the physical realm and some sort of demiplane of dreams.