For me, I did Siege of the warmind. The one you're doing is good as well, but I just found it much easier in the warmind having all the thrall run towards you and not having those few that run around the rocks on the moon and act like you aren't there. I put it on the highest light level, went in, and stood there shooting them all 1 by 1 as they run towards you in a straight line, moving up towards the Omnigul room and wiping before you go in and do it again. Not sure which of the 2 will get you the kills quicker, but just a thought for ya.