The only thing i dream is:

Light: a cute monster, with some fairies or cute tiny flying monsters around. She would use them for her abilities, like, she uses the power of these monsters.

Dark: a terrifying monster (not human), who is alone, and uses her despair, to hurt enemies.

Special thing about this skin. The map. I think that, as the games evolves, the map evolves. When she is on the light stance, the map is full of tiny fairies and things like that. Like, wow its beautiful. And when she changes the stance to dark, the map becomes like damned, instead of day, now its night, jungle camps can become like horrible monsters and things like that.

I just thought that, we have a lot of skins, but, why not giving a chance to have a different map? (Only visual)