Hi

One of my players has a crystal skull and was possessed by a demon and first I was like "well I could use that to give the players some oracle like talked" but now.... I have a funny idea

We currently play "Tales from the Demonlord" and my idea was that the player together with the Halfling master of the cult wanted to call a demon prince to the world making a sort of pact. It partly succeeded...the player got his memory erased and part of the price is now in the void, in the skull and in his mind (I don't know yet if the temple in the 9th adventure got raided by the paladins or... something happened). The sword they summoned now can only be wielded by the possessed character to kill Katandramus

Considering they will have "a talk" with the demon prince. What possible benefits would a demon pact give you. What ideas do you have??