Sacred Haven of Debauchery

However, in the first part, it's much harder to kill him.

The most challenging battle I remember, at least in the first part, but I still managed to kill him.

In the second one, I didn't kill him; instead, I summoned him to help me in a battle against the enemy.

Yes, he seems to be quite effective against vampires; you can just stand aside and periodically heal him.

Added 2 minutes later
Um... why do you have "Heroes 7" in your signature? After all, even the sixth game hasn't been released yet...