It's on test server, staged all to hell with maximum buffs that you'd never realistically have ever, but still, it's pretty fucking ridiculous. GG elemental shaman?
edit. ok, here's the breakdown of what happened. Basically stacking of Stormstrike. That's gonna get changed

It has been done with about 10 stormstrike debuffs on my target.
It would have been possible to get 16 debuffs on the warrior.
Formula:
((1.20)^16)*1.20*1.30*(CL crit with zhc)= damage
This is for a warrior doing recklessness and a priest doing power infusion.
My suggestion:
Change stormstrike so it doesnt stack many times. But give stormstrike an unlimited amount of charges (make it a real debuff) for its whole duration. Then, it would be like a warlock curse (20% damage increased nature damage for 12 seconds).