I have double checked this guys : I had one scroll of BOOK of EVIL and after I clicked "USE" on the book I defeated and had to deliver to Mr. Necro, I just had 2 of them ... so the "use" does something- it even works - and it gives you one scroll of Book of Evil in your spell book...(I have 1.7 version FYI)
BTW - the necromancer did not sell Book of Evil scrolls - He was selling only 3 scrolls of Greasy Mist... - so it looks like it is not always that he sells this spell (or maybe he sells it when you don't use the BOOK - so you will not "tear out" the page with this spell
