I feel this submission veers off in multiple directions without much focus. You have the scatalogical, followed by its use to magic-users, and finally some kind of reaction to non-magical folks?
It goes every which way without really providing the meat of how this tome is malicious. You mention using weak-willed mooks to do its dirty work, but what is it trying to accomplish?
Also, foul thoughts seemed to have nothing to do with the actual item.