After a lot of thinking, I was able to beat the crypt on my first try as an Elven Paladin worshipping GG. I spent a lot of time somewhat aimlessly killing things, not really sure how on earth I was going to beat the boss. But then I was down to the boss and 3 other vampires on the map -- I crunched some numbers and realized I was actually going to be able to do it.
That is a brilliantly designed boss!
Are there supposed to be any other quests at this point? I have 4 dungeons unlocked that I haven't beaten, but no associated quests.