Abilities:

• Frozen Mallet - Attacks have a chance to apply Frostbite!  Frostbite inflicts 1950-2050 damage every 2 seconds for 20 seconds.
• Frozen Orb - Summons a Frozen Orb, inflicting 2925-3075 damage every second to everyone within 8 yards.
• Whiteout - Increases frost damage taken by 20%
• Freezing Ground - Immobilizes everyone around the target for 4-5 seconds.

The Fight:

Two tank fight.   Frozen Mallet forces tank switches if the DoT gets too high to handle.

Every 30 seconds or so, he'll summon 3 Frozen Orbs (1 in 10 man).   They'll go around doing frost damage to anyone near them.   Raid move away.  Range dps switch to kill them.

Every 45 seconds or so, he'll do Whiteout to the entire raid.  More frost damage taken, soft enrage mechanic.

Finally, Freezing Ground is just a Frost Nova rooting several people.   Dispel them in case Frozen Orbs are up.