Vigil of the Cursed
Spirits are similar to ghosts in one respect, they have died. That is usually where the similarity stops. They are ghosts that have moved on into the shadow realm and can no travel back and forth. They usually come back to fulfill some purpose in the world. This could be protecting, making things work, fighting off ghosts, or helping ghosts move on. There is an endless list of what they could be doing. They also do not have anchors and seem to be more powerful than ghosts when it comes to having to appear and what not.