Soul energy, all that was and probably all that would be, a fundamental building block of reality right besides Mama, Qi, Chakra and probably whatever energy out there the people cultivate for strength. Each more different than the last, focusing on a different path to power. But regardless, there was one thing that was constant through all of the universes, and that was the soul. Even objects with a sufficient amount of feeling attached to them develop souls of their own, either living or dead, and being a god of souls practically gave me domain over life and death.