I don't know how much he can debuff people, but a 14 seems pretty easy to hit. Honestly, I think having the BSF guys beating it with a stick might be one of the better options. Unless the Vampire can control undead or something.
Edited my post in the game thread, btw. We'll see what happens...
Also, Tshern, did you ever find an answer to my question about Steal Spell? It wouldn't apply in this encounter, but I'm still curious.