[Flaming Fist Enforcer]

First go sw into the room with gargoyle statues, and click the 2 clickable ones. Go back to the center, and then se into the bedroom. Durlag appears here, but turns into a doppleganger. Now you can go to the nw room, the one with all those dummies (not sure if you have to pick up wardstones, but do so anyway). When you attack the dummies Durlag appears again. When you kill him the door to the ne should be opened and you can go through.

Btw, when you get through those doors and battle begins iirc the doors close and you can't get your chars (who stayed on the other side) through them until the battle is over.