Once you get to Kael you have your pet on one side of the two statues of him and you stand on the other. Hide behind it until he does he emote for his mind control, pop out and put some dots and a couple shots into him then hop back into cover. It is no where near as dangerous as it used to be since your pet can eat a lot of his attacks now with zero problem (I was using a turtle fyi). I started doing that with only a couple pieces of heroic gear at 90. With a full set of heroic gear he is super easy. I would hate to imagine how easy he is once you got some heroic raid gear.