I just offered the most cliche Devil’s Bargain, the one I never thought I’d actually get away with: one of my player’s characters just promised his soul to the Dimmer Sisters for their assistance in retrieving an Artifact of Kotar.
The funny thing is: The Archivists, a crew of knowledge keeping assassins, just learned the ancient technique of the Emberdeath, which another character has promised to use on the pledged upon his death to rob the Sisters of their prize!