When he raises hammer - Run

Correct me if I'm wrong but when he activates this ability he stays in place so move just a bit away from him. Be sure though to aggro him with your paladin afterwards or he'll just make a big mess out of your group. And of course, stay at around 20y from tank. It'll do it.

Just checked, he has:

Attacks and abilities - Solutions in orange Bold
  • Shadow Power: Enrages glowing red, 100% attack speed increase. This buff can and should be dispelled by Shaman's purge.
  • Jack Hammer: Does an AoE centered on himself hitting for around 1000-1500 on regular and about 2500 on Heroic around 8 times in a short time. He stops moving when he does this, so all you have to do is run away to avoid it.
  • Poison: Has a poison ability that reduces attack speed and armor by 35%. appears to be a frontal cone. Poison Totem/Cleanse Spirit/You choose .

Those stats are more than enough.
Be sure to have HS always up. Don't hesitate to use the 50% damage reduction shield if you have already endured long in the fight.
You're not that far from being capped in defense, just check how far you are from being capped in avoidance (use the macro).

Things really changed for me when I capped at both.