I don't know if anyone else has mentioned this but I'd love to see something like Tieflings from PS:T. The Idea of a humanoid creature with a sort of very powerful but also mysterious and kind of supernatural lineage is very interesting to me. Their could also be some cool game mechanics relating to the soul magic aspect. I.e. does the spawn of a god or demon have a soul, or a different type of soul? Would they be susceptible to different types of demon summoning or command. Maybe they'd be more powerful but have certain vulnerabilities.
