Nighthaunt

A Nighthaunt is a type of immaterial form of Undead usually called a gheist or wraith in the service of the Grand Alliance of Death commanded by Nagash, the god of death. It is the spiritual remains of a once-living mortal that has become afflicted by a magical curse that leaves it so twisted by the pain, bitterness or regret they suffered in life that they now seek only to spread this darkness to others.