The spellbook is basically a "companion" book to the "Necronomicon". "The Necronomicon" talks about Sumerian magick and occult spells, formulas, and myths, all of which are supposedly very scary and dangerous to practice. The spell book distills everything and serves as a sort of safe guide for practicing what's in the "Necronomicon". Apparently the spell book is pretty short and very out there. It's more likely something that only those who have read the "Necronomicon" will pick up.
