Sacred Haven of Debauchery

I killed a black troll with a demon.

But the dragon attacks skeletons and doesn't touch you.

It seems that magic has very little effect on it, although I don't remember for sure. Oster, he's a dragon snapper, here's this cutie:

Added 3 minutes later
I killed the swamp dragon manually with the help of two mercenaries, and I think I killed the stone dragon with fire rain (two spells) and finished it off. I tried many things against the Fire Dragon until I finally turned into Oster and devoured it. I think I also killed the Ice Dragon with rain spells. In general, dragons should be killed manually by a mage (when I played "Return," I was a Necromancer, it was just a magical duel: I run away from his shots and shoot back, but in this add-on, the dragon somehow didn't have regeneration). And I killed the last two with the fire rain rune