I haven't found a way yet to interrupt his healing. So far all CCs I've tried (Knock back, Stun, and Drag) he resists every time. Am I supposed to use an elemental cc like lightning or frost or do I just have to respec and get cc penetration? Also, I tried to attacking to see if there is a certain dmg threshhold but he still just kept using his healing ability and was not interrupted. Thanks all!