Avenging Spirit

Avenging Spirits are born from violent or unjust deaths. They produce spirits of vengeance that will keep returning to repay the damages delivered to the one whose death formed the Avenging Spirit. The problem with Avenging Spirits is that they make no distinctions of culpability: they will simply seek to kill any and all involved in the unjust death, regardless of whether or not they are actually guilty.
When an Avenging Spirit forms, it's existence is physically tied to an object or place, either of which must be important to the unjust death. The only way to permanently kill an Avenging Spirit is to find the object or place and either destroy or exorcise it.