Blood Sigils
Should a player become "Branded", they are doomed to immortality. No matter how eviscerated or obliterated their body ends up, they will ressurect by means of Accursed Blood at a Blood Sigil.
Much like life however, Death is a painful and draining process. Everytime one is ressurected from a Blood Sigil, they will not only lose 1 Composure, but take a -1 to all Attributes, but +1 ID. Once all Composure is lost, so is the character.
By what means, is up to the context of the story, player, and GM. Whether the Character has gone to complete insanity, transmutated into a Demon, or dissapears from the face of the planet.