Has anyone organized an actual kill yet on the PTR? Do we have any idea how often he does the zone-of-death and the chain lightning, how often he gets the 10% stacking buff? How many seconds between tank-swap mechanics, how long does it take to fall off?
If we've got those numbers we can math out and out how many tanks and healers you'll need, and how many 100k dps players it'll take for a kill within 'x' seconds.