How to Defeat the Necromancer in a Battle to Death

We find an altar dedicated to the one eyed god of death, Vecna. Also on that altar is his spell book. Ehrlich: I'm kind of interested in taking the spell book and learning necromancy myself. Go ahead and roll a D 20 to see if you can learn any necromancy yourself. The shadow of your hippo suddenly peels itself off the floor and becomes spookily like a dementor starts like move around.