Monster World: The Golden Age (Monster World: The Golden Age #5)

Just as things look bleak at the Conway farm, help comes from the most unexpected of places: Nybbas, demon of knowledge, who has been harboring a grudge against Belphegor, Behemoth, and Enepsigos since the dawn of time. But it's going to take one hell of a sacrifice to pull off the spell he tells Hank to use!