Conquest of the Horde

I'm planning on writing a set of different rituals for my guild RP, but I was wondering. When it comes to demons, should I:

A: Find already made demons in the lore
B: Make up my own demon.

Say if it was for a ritual which would seduce someone into doing your bidding, make up some succubus' name, whom's you'll use to call upon their power. It's different to actually summoning the demon, it's invoking their power for one specific thing.

Um...I'd have put this in PD, the GMs will know this xD

Use demons already in the lore, please. And nothing too powerful unless you work out a storyline with the GMs like the Deadeye Watchers have.