I tanked Keleseth as a warlock. I was assigned range tanking so I prepared myself with 2 stamina trinkets (from the brewfest event) and the 3 parts of the Glacial Set (cause it has much much stamina). I had something about 29k unbuffed. In our first try I was wearing my normal stuff, no stamina equipment, I gained the initial aggro with 2-3 Searing Pains and then I started my normal Destro Rotation on him, the first Nucleis was popping up then and I castet CoA on it. I did a mistake in the first try, I was casting the highest level of CoA which can kill these nucleis very fast, and the first Shadow Lances from Keleseth were hitting me hard. We wiped cause one of our healers died. In the second try I equipped all my stamina gear and I activated "show nameplates" so targeting the dark nucleis becomes easier and sometimes you can't target them properly when a healer has aggroed (studid word) them. Everything worked fine here and I gave the healers much more room for healing me, since we had only 2 healers. I think when you have 3 Healers you can overcome equipping any stamina gear or spec, but I don't really think its that much needed, when you gained some stacks of these nucleis you get very very little to no damage. One of the easiest encounters I've seen so far, just get along with the abilities of the princes and their empowered versions and thats it. Our healers really did a great job, so did the rest I think.
Warlock (Destruction with survivability talents and some gear, but optional)