Dream vestige

A dream vestige was 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 was accompanied by a chorus of faint voices, some moaning, some gibbering, and others laughing. The souls that made up the cloud were in constant torment, trapped in a nightmare, and they hated one another even more than they hated the world.

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

It burned with an insatiable hunger and snatched up living beings with tentacles protruding from its mass, dissolving them into nothingness. Only mindless undead beings such as zombies, skeletons, and golems could endure its touch.

A bard or someone able to weave emotions could defeat the entity by enflaming the dream vestige's wrath and self hatred until it would be strong enough to overcome any constraining forces and dissolve the fog-like entity. While suggested by the authors liberal flavouring, it is however not supported mechanically by the 3.5 DnD rules, and should not be assumed as factual beyond author liberty.