He obviously meant threath necromancer. "Threath", for those who aren't aware, is short for "threat of h.", the "h." referring to Preparation H. Thus, the threath necromancer is a wizard who can raise (lower, actually) problematic hemorrhoids in people who have a history of them. Niche character, to be sure.
Sounds nasty. But paladins will always be a bigger pain in the ....