Marshlight
Marshlights are ethereal creatures which take the form of glowing lights; they can appear to be lanterns, vaguely humanoid figures, or other crude shapes. They can neither wound nor be wounded, although magical weapons may drive them off. They are dangerous because of any physical damage they cause, but because of the compelling hypnotic effect by which they lead mesmerised individuals to their deaths. It is thought that they feed in some vampiric way upon the ebbing life-forces of their victims.[1a]
Marshlights have no physical form, but can appear as glowing lights of indistinct appearance or as luminous humanoid or animal figures.[1a]