Our raid group 1 tank and 2 heals it. DK Tank, priest and druid healer. Bring him up to a minimum of 15 stacks for the first phase 1, let Thok run around 6 times, then transition. the next phase 1 would be 8-12 stacks. Repeat 6 fixates for the next phase 2. When/if we get to fire phase, transition at 1 or 2 stacks and burn the boss.
We get him to about 20-30% by the end of the second phase 1. I'm not sure if that counts the heal he gets, I never really pay much attention to that. You roughly want to him 60% when he goes into the first fixate phase though.
For all the phase 1s, we split into three groups. 4 in melee range, 4 slightly over 10 yards behind melee. 1 to the left of the ranged group. They form a triangle roughly the diameter of an efflorescence.
On the topic of classes, we have this comp:
DK Tank
Disc Healer
Druid Healer
For DPS: Lock, hunter, balance, warrior, paladin, mage
You absolutely want a paladin for this fight. Two BoPs and Devo aura are the most important raid CDs. If you have the option, bring the resto shaman too. Resto druid is superior to disc, but it depends on your individual healers more than anything.
(
http://www.worldoflogs.com/rankings/...irsty/10H/hps/ Resto shamans occupy 44 of the top 50 spots)