Remorso

The Primeval Demon Remorso is the personification of regret. His domains are guilt, heartache, shame, regret, remorse, grief and anguish. He feeds off of those feelings while on the mortal plane. To summon him, there must be an exceptionally powerful, magically induced decision or action that imbues an area with one of the feelings under his domain.

Being a primordial demon, Remorso cannot be killed, only banished from the mortal plane. While banished, Remorso patiently waits for some poor fool to casts his regrets onto the world; Remorso's next opportunity to spread anguish among mortals.