When going for the mission achievement "Dodging Disease", this task was sort of a pain to 2-box; esp if the AE targeted the main tank. Ran it probably 7-8x and did, what I thought, was a great job kiting the AE while I burnt Xulus with tank/merc. However, the AE box seems to be a bit larger than the particle effects show on screen and somehow it would always grab the kiter, or path too close to the main tank.
Solution? Ran Xulus down to 40% so he casted both his AE spells and let myself die. The AE spells will not reset if you wipe/reset event. Rez'd and zoned back in. Killed Xulus, (which is effortless at this point) and got achievement with no worry of the AE.
Wish I knew all this before hand - would have saved some frustration. Got my achievement and Here AA's now!