Grave Mists in the Ghostwalk Champaign: Grave Mists have no interests in feeding on ectoplasm, and therefore ignore ghosts (unless the ghost attacks them first), favoring the life force lingering upon corpses and the living.
A dead PC who was killed by a Grave Mist has their spirit blighted and raised as another grave mist as the Crate Spawn ability normally, The PC’s soul trapped within a befouled envelope of unlife, it cannot enter the veil to either manifest as a ghost or cross over until its cursed form is first destroyed. This does not include any future grave mists it creates, although should it have created other spawn before being destroyed and manifesting as a ghost, he loses control over them and turns against him and any living closest by. After being destroyed, should the spirit wish to manifest as a ghost, a saving throw (DC 15 fortitude) is required. Should the PC succeed he/she manifests normally, failure indicates the festering taint of the grave mist still remains, and the ghost’ appearance is always manifests in the gruesome category no matter what wounds the body sustained before death. A gentle repose spell cast by a 5th level spell caster purges the lingering blight from its ectoplasm allowing the ghost to appear the way it should.
A ghost PC slain by a grave mist on the other hand does not become another grave mist, instead the raw ectoplasm remains intact for 1d4 rounds undergoing a blighted metamorphosis into a new necroplasm (Ghostwalk p. 168). Not until the same necroplasm (the PC’s soul infested by blight and not any others it may have created itself) is destroyed and the imprisoned soul freely pass through the veil into the true afterlife, can the body of the PC be raised from the dead normally.