Well we only got to spend an hour in ICC 25 heroic, but at least we downed Marrowgar on the 1st attempt. The fight was surprisingly easy but the 30% buff and the fact that at least half of us have done it regularly on 10 man probably helped.
On to the strategy itself it did not vary much from normal mode. In heroic mode he has more health, hits harder and casts bonespike even during Bonestorm. There are also more Coldflames and they hurt a lot more, so be ready to move. For Bonestorm we split our raid into 2 groups with one group going left, one centre and one right.
It is imperative that all DPS switch to Bonespikes when they are up an a /tar Bonespike helps a ton (/tar Bone should be enough) for quick target switching.
We did move on to Deathwhisper but spent our 4 attempts wiping, although our progress improved the more we changed our strat. The best strat for us, it seems is to have everyone behind the boss forcing the adds to come to us and we then AoE them down with splash on the boss.
Well we'll see how we go tomorrow.
keep on hunting,