The book he carries is a magical chronicle. It originally belonged to Erodon, before he turned evil, and lists information about just about every being in the universe. It's a sort of bottomless book that seems to have infinite pages despite being about the size of a roughly 250-page novel, having no consideration for physics. The only catch is that whoever owns the book can only see the information on a certain being once they know of their existence, because it hides itself from them otherwise.
Don't feel like properly formatting this page at the moment, so will finish later.