I was able to beat him before the patch by having my ret paladins in a star pattern around the boss. That way, each character only gets one stack of the smaller dot. It was easily healable with flash of light procs, so the only concern was taunting him back into the middle after he surges.

Since the patch, I converted my rets to holy and this boss is much easier, even in the rep vendor blues/epics for healers.