Chaos Zakum, how hard is it?

So I just saw 2 ss'es of 2 diff runs, both being less than 5mins before the whole squad was wiped out. The problem they posted was that dispel was every 3-5 secs. Leaving no time for bishops to heal, because they constantly have to MG. So unless GMS gets the auto skill item, will czak be unbeatable? Or is there a way to get through the arms.