Yesterday our team went up against our final foe inside of Karazhan, Nightbane. Unfortunately, we have not been successful at defeating him yet. He keeps killing our healers which is a problem no matter how you slice it.
We tried a couple different strategies and at one point he only had a quarter of his life remaining. We are getting close just not making it all the way.
Some of the healer problem is their fault. For some reason our priest really likes standing too close to the dragon and then getting hit by his giant claws. But mostly it is the skeletons Nightbane calls to his aid while he is safely in the air.
If anyone has any tips as to how we can keep our healing team alive, I'm all ears! Our raid set up is a pally tank, druid off tank, a pally healer a priest healer, and the rest are assorted fighters.