Group 1 - 3 stacks
Group 2 - 3 stacks
Group 3 - 3 stacks
Group 1 - 6 stacks
Group 2 - 6 stacks
Group 3 - 6 stacks
Group 1 - 8 stacks
Group 2 - 8 stacks
Group 3 - 8 stacks
Group 4 - 3 stacks
Group 1 - 9 stacks
Group 2 - 9 stacks
Group 3 - 9 stacks
Group 4 - 9 stacks
Healers - 9 stacks
We usually switch to burn boss before healers get up to 9 stacks because the last boss is already pretty low. Our group 4 consists of our lowest single target dps.
Our group 1 is the add kill group and they are off to the side only until the rotation where the groups are going from 8 to 9 stacks. also once the add group stacks with everyone else we have group 4 going and killing their own adds with help from group one if needed
my raid is 10 man, but the Group stacking is the same.
Group 1: 7
Group 2: 7
Group 3: 0
Group 4: 0
Group 1: 8
Group 2: 8
Group 3: 7
Group 4: 0
Group 1: 9
Group 2: 9
Group 3: 9
Group 4: 9
After Group 4 got 9 stacks our healers stacked.
Group 1: Arcane Mage & Balance Druid (rangeds)
Group 2: Survival Hunter & Shadow Priest (rangeds)
Group 3: Rogue & Warrior (melees)
Group 4: Feral Druid (dps) & protection Paladin (melees and tanks)
"Group 5": Healers
We had no warlock, so our Balance druid and hunter slowed and killed the adds. That's the main reason why we had a hunter in Group 2. You should take arcane mages, affliction warlock, shadow priests and Balance druids in the first Groups as much as u can.
If your DPS Players have nice gear u won't reach the Group 5 (healer Group), u will be able to kill the Boss while Group 4 is stacking. If the last Boss will have about 15% hp left u can ignore the adds and kill the Boss(Boss will die before getting 5 stacks by adds). Use Bloodlust at around 70% hp of the last Boss.
In the last Phase the most important Point is the cooldown Timing of your healers. Wrong timed cooldowns will let u wipe for sure. The second Phase (where 2 bosses are alive and kaolan is dead) is the hardest Phase. U Need to dodge thunder storm, dispell the Boss, kill the adds and have the right Group in Position for stacking.
EDIT: The reason why we stacked like this (grp 1&grp 2 high first) is that u can manage the 2nd Phase of the Boss more easy then stacking like 3-6-8-9 with several Groups. Thats because u take the high dps single target classes in Group 1 and Group 2 and so Phase 2 Boss will die much faster then having more Groups on about ~5-6 stacks.
Water bolt interrupts should be a rotation of 4ish.
It's arguable as to whether to let Regail spam lightning bolt or not. A block tank will get more vengeance and generally take less damage if they're interrupted. DK might do better if they're not. On either 10 or 25 it's usually solo tanked and the tank's damage on the appropriate boss will be the highest.