I haven't found this aug-dropper is "the roughest." I've been 6-boxing all these since the level cap went to 80 and, frankly, Vilria the Keeper seems harder to me.
The roughest mob, without a doubt, is First Lt. Minas. He's even a b*tch to pull since he wanders a long path at the top of 2 staircases, and he runs very fast. Plus he flurries constantly.