(Edited due to having done it on the mage and shammy as well as Kurn, updated with more information.)
Having just done this on Kurn, I got a pretty good look at how to do it.
You’ll need two tanks, just like all the other VOA bosses. We did it with five healers, meaning 18 DPS. On 10-man, we also needed 2 tanks but we successfully 2-healed it with me on my shammy chaining off the active tanks and a resto druid healing the raid, leaving six DPS.
Tanks will get stacks of Frostbite (10 / 25) on them. They should taunt after 3-4 stacks. Our tanks were taunting after 4 stacks. On 10-man, one of the tanks didn’t really know how to taunt properly, so one tank was getting 6 stacks while the dude who couldn’t taunt on time was getting 3 stacks. This was, surprisingly, not too big a deal, but your mileage may vary. Frostbite leaves a dot behind, though, so keep healing the other tank.
Ranged should kill the 3 Frozen Orbs (1 on 10-man) that pop up. They pop up with such annoying frequency that they screwed up my rotation on Toravon a lot. Figure it’s about 30 seconds or so. They have an 8 yard or so AOE attached to them as they float by. This WILL do some AOE frost damage if you’re too close to them. That’s why it should be ranged DPS to take them down. (Arcane mages, Frost Ward proccing Incanter’s Absorption is seriously amazing.) Note that Frost Nova is ineffective and I would assume so would other frost-based slows/stuns/immobilizations such as Freezing Trap, Frost Trap and Chains of Ice. Not sure about Earthbind, Entangling Roots or things like Hammer of Justice.
Every so often (45 seconds, I believe), he’ll cast something called Whiteout that increases the frost damage taken by 25%, which stacks on the whole raid. This also does a lot of AOE frost damage to the raid and eventually, it will be unable to be healed through. All of my raids got 3 stacks for 75% extra frost damage. We had Frost Resistance Aura or Totem up for sure. I don’t know if any paladins used Aura Mastery, but I’ll try it out and save AM for the 3rd cast of Whiteout. (Which makes me think of Liquid Paper.)
He’ll also occasionally cast something called Freezing Ground, but I’m not sure why he’ll cast it. Not having a melee DPS class and not having tanked it yet, I don’t know if it’s dispellable, if it’s significant or just annoying.
So, to recap:
– tanks will need to taunt every 3-4 stacks of Frostbite. These stack up QUICKLY so be ready to taunt. Deadly Boss Mods will count the stacks for you or you can edit your raid frames to show you Frostbite as a debuff and keep track of it yourself.
– ranged will need to kill frozen orbs. Think of it as on Emalon, that if you don’t kill the Overcharged minion, you wipe the raid. Ranged MUST switch over or else they’ll float happily through the raid and kill people with their AOE. Melee, you have it easy. Stay on the boss. The whole time.
– healers will need to heal the whole raid up every 45 seconds or so (from Whiteout) and be sure to keep healing both tanks due to the dot that Frostbite leaves on the tanks.
Easy as pie. Enjoy your T10 and Emblems of Frost! He drops T10 legs and gloves (ilvl 251 on 10, ilvl 264 on 25), plus some PVP gear, plus 2 Emblems of Frost on each difficulty.
Have anything to add? Drop me a comment and I’ll update the post appropriately!