What is the most effective book of black magic?

This really is subjectional information... really your own Book of Shadows is your best book. Answer

Just dont practice black magic in the first place. You'll regret it, trust me. Ok, I believe someone may have tried to edit my last answer. If your interested in Black Magic there are countless manuscripts containing demonic invocations that you could consult, they are easily found and obtained, but I will not list them. If you want to study black magic, or invoke evil spirits you will be met with entities you wish you never encountered. Study the light, invoke pleasant beings, if you want rituals as such PM me, otherwise, avoid your current pursuits.