Boxing with a 105 Ranger and Mage with 2x Cleric Mercs, I'd wiped about 5 times just trying to break into the room. This morning I finally had success.
Using an eye, harmony the room. Then stand right outside the door and let 2 of the 6 mobs proximity agro you (Probably didn't need the harmony). Pull these into the hall and kill. Rinse and repeat.
Spawn times are about 10 minutes, so if you can space the kills out a hair, it will be much easier for you.
It took about 5 clearings before The Fallen Noble spawned. She is a little harder than the normal trash, but not all that hard of a kill.