Moving him away from the Krosh-tank is important to keep him from knocking the Krosh-tank into Krosh's Blast Wave. An alternate strategy is to tank him with a feral druid, as they are also immune to the polymorph.A feral druid meleeing him will definitely take more damage than a ranged tank, but it is a fairly simple strategy, and more comfortable for many guilds than moonkin tanking.A warlock is still need to Fear and/or Banish the Felhounds.
The Lightning Bolts are nature based and the arcane shocks are arcane based but both do relatively little damage.
One healer is typically enough to handle the damage.
This action shifted the balance of power from the Boulderfist to the Bladespire, and drew the attention of mighty Gruul himself.
Fanatically loyal to the gronn, Maulgar now serves as Gruul’s right hand and the guardian of the gronn lord’s lair.
This saves the tanking mage from a couple of hits too.