The Phoenix Charm is a spell bound to the body of someone by an arcanist, presumably so that it is permanent (or effectively so). Only known to have been used by the most powerful arcanists, this spell consumes the target's body, making it impossible to take the person alive and torture or coerce them.

It is not clear what triggers the Phoenix Charm, whether it's the target consciously doing so or the arcanist, through some means of scrying on the target.