Phase 1: Tank

For Lord Marrowgar, 1 tank grabs aggro and pulls LM back to the circle in the center of the room and turns him away from the raid. The 2 off tanks stack on top of the tank to help soak Saber Lash. Melee moves in and attacks LM from behind and the ranged and healers spread out in a semi circle around the room.

Throughout the entire fight (Phase 1 and 2) LM will cast Cold flame at a random (currently presumed ranged) target. This is a slow moving line of blue flame that is fairly easy to avoid. Melee needs to be especially careful since Cold Flame will be spawning right on top of them.
Note: If it is indeed targeted on ranged only, then it may be a better idea to have all of the melee stack on LM's back right and all of the ranged spread on the left half of the room so that melee never have to dodge.

Also throughout Phase 1, LM will cast Bone Spike Graveyard which will impale 3 raid members, excluding the tanks, on Bone Spikes. All DPS needs to quickly switch to the nearest Bone Spikes and burn them down, as they do 10% damage per second to the player caught in them.

Phase 1 last for 45 seconds on the pull, and then 1 minute 10 seconds after that. Most of the damage in this phase can be avoided or kept low if people avoid the Cold Flame and DPS down the Bone Spikes quickly.

Phase 2: Whirlwind

In Phase 2, LM will cast Bone Storm. Bone storm does damage when it hits a player as well as puts a Bleed on the target that last for 15 seconds. Since he also cast Cold Flame during this phase, it is best if everyone stays out of range to avoid getting hit, bleed ticks and Cold Flames damage all at the same time. Clothies especially should avoid him.

He will begin spinning and pick a random target who he will quickly move towards. Once he reaches his target (or where they were at) he will cast 4 Cold Flames (one ahead, one behind, one left, and one right). He will spin there for a second or two then pick a new target, charge, and again cast Cold Flames in 4 directions.

It is possible for Ranged to DPS during Phase 2, but avoiding Bone Storm and Cold Flame are first priority. LM does not cast Bone Spikes during Bone Storm on Normal mode.

Bone Storm last 20 seconds.

Once Bone Storm is finished, aggro is wiped and the Main Tank must re-establish aggro. LM is untauntable, so Tricks of the Trade and Misdirect should be reapplied and DPS should focus on getting into position before they begin DPS'ing to allow the tank to build up a lead.

*Note: Melee should be aware of where the tanks are, as Saber Lash can be deadly to a non-tank who ends up in front after Bone Storm ends.