I am interested enought in that ideas to say, speak
My idea is that in my universe the power of a person as its own personality too.
Lets say, when to big powers collide they created beings composed of both powers, of course they arent as powerful as their creators when born, these beings take features of both of the users of said powers.
The Nihiliums powers were so great that they manifestated themselfves on the world as two materials that already existed.
Blackdust and Blackmist.
When their power touched each other, they created either sparks or new beings.
Of course these owners of said powers could still reproduce biologically, and they can also mix both methods.
What do you think?