[@Genni]

First before I answer your question. I enjoyed reading your breakdown. You are 100% correct, the combinations allow strengths and weaknesses. There's a sort of balance inherently put it in. But I can say with full confidence I'm not sure if everything is balanced. I feel like someone will find a way to break it.

[quote=@Genni]
How would you feel about a Seraph-Nayu hybrid who had the ability to affect the darkness in their target's soul?
[/quote]
It needs more details. Darkness in a soul is I assume you're equating to malice, or some kind of inherent impurity in their souls. Most forms of darkness is either legitimate shadow, lack of light, or a manifestation of shadow, An otherworldly property. Again I'll need to know more about it to determine if its possible given the bloodline you stated. So far it is close.

This question has led me to make another rule, or rather explanation.
[color=red]Combing / Creating Spells, Powers, & Abilities:[/color] When a spell or power comes to mind that is unique in a way you are not sure what category it falls under. Ask the Game Master "Me, Rai" what your detailed power or spell will fall under. Explain how its activated and what effect it has on opponents. Whether its possible for your bloodline to do so or not will be determined by a careful study of the properties of your spell and which parts of it fall into what category of spell casting.