Mage: The Gun Quarter
The other self. Countless theories exist on the nature of an avatar, but none can deny their existence. It is said that every person possesses one, though few will have their avatars awaken in their lifetime. An awakened avatar is what allows a Mage to alter reality and it is this part of their selves that is allowed to reincarnate. As a result, many avatars carry the memories of their previous mortal lives, though not all mages are able to access these memories.
The Technocracy and Nephandi have very different views on the nature of avatars and approach it in their own ways. The Nephandi are capable of an unspeakable ritual known as the Caul, that permanently inverts an avatar, metaphysically turning it inside out, so that rather than pursuing ascension, it pursues a descent into oblivion for all future reincarnations.
Very powerful Mages and Technocratic scientists specializing in Spirit magic and Dimensional Science respectively, are able to permanently destroy an avatar, though this is typically reserved only for avatars that have been subjected to the Caul.