You're right, a couple levels won't help, but 4 or 5 more levels will. =) Keep in mind that I went through the SE Wilderness when I was level 18 or 19...not through any predetermined purpose, it just took me that long to get around to doing it with all the stuff there was to do on the 'west' side of the world.
If you can cast Soul Shield and Element Shield in the first round at high levels, then you should be OK. If you're not able to do this yet, it's probably best to wait until you are. It's always good to cast Purify Air every couple rounds or so as well (you should have found a ring by now that casts it if you don't have it yet), just in case that Death Cloud gets through your defenses. Once your defenses are up, just run forward as fast as you can and hack away at the Death Lords followed by the Sorceress Queen.
Another tip: Cast X-Ray, then walk out and stand in the entrance-way to the huge room for a few seconds, then duck back out behind the wall. When I did this, the Sorceress Queen and the 2 Death Lords started moving towards the doorway, leaving the Cultists behind. They won't come all the way to the door, but quite a bit closer, so when you go back into the room and combat starts, you'll be able to close in on them much quicker (again, don't move 'til you have all your defensive spells up).
Hope this helps. Good luck!