These beings are the corrupted souls of dead sentient beings.
They are intelligent but the pain of their own existence is driving them to insanity, causing them to haunt and attack any living creature they can find.
Often bound to a location or object they can not go to new locations without assistance.
Those that often deal with ghosts know they and most of their sub-classes are unable to cross barriers of salt such as lines, circles or squares of salt poured on the ground.
Perception and Sensory Capabilities
Hearing, sight, can sense life energy