BB and RoS are the first boss encounters in T6 that are challenges. BB isn't even that bad it is just a test of healing.
RoS is going to test a couple things.
Phase 1. Easy sauce, no one should die. Assign a tank rotation, 11k health or more. As soon as person gets aggro they move out of hit box and next person moves in (important). Simple as that.
Phase 2. Biggest learning curve for us was Interrupt rotation and teaching dps not to kill themselves. The damage dps takes from the damage they do seems to be a little bit behind in registering, so you will see guys crit and think they are safe only to take 5k damage just as they cast another spell to take 5k damage again before healer can top them off. Curse of Tongues up at all time to help those on interrupt rotation. If they mess up one of your dps is going to die. The dps needed to get through the phase before the mana burn isn't that bad but it needs to be solid so dps need to fine that line where they get top dps but dont kill themselves. Assign healers to groups and such.
Phase 3. Soft enrage timer with the ever increasing Shadow Damage. Use nature resist pots (much more effective than SR pots). Have OT grab boss, then MT grab it off tank. No dps at all, no dots, wands, auto attacks, debuffs anything. Why?
Seethe
Increases threat generated by 200%. Lasts 10 seconds. Only cast when the boss switches target, either from aggro pull or Taunt. It is therefore possible to avoid Seethe ever being cast.
10 seconds gives your MT a threat lead that your DPS will never catch up to. As soon as the debuff is gone call it on vent and DPS goes balls out. Heroism, haste pots, destruction pots, trinkets etc. You have 100 seconds to burn 3 million hp.
2 pallies and a Druid on tank, he will be taking spike damage and if heals are pull off him for a second in this phase he will probably die. You want 2 CoH priests, and 2 Chain heals as well, very raid healing intensive hear. Feral druids, Balance Druids, Resto Druids doesnt matter should pop Tranquility mid phase when raid healers are getting swamped.
Should take you a couple attempts to feel out each phase. There is a big onus on DPS in phase 2 not to kill themselves, pressure is also on interrupt rotation not to miss a spirit shock and at the same time not to interrupt a deaden.
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Bode - 100 Holy Paladin - Lightbringer