Lord Marrowgar killing strategy

The first boss you’ll face in the Icecrown Citadel dungeon is Lord Marrowgar. He guards the Frozen Throne in the Lower Spire. There are two main things to remember when battling this boss. First, don’t stand in the fire he shoots across the floor. Second, when he starts to spin, run as far away from him as you can.
Lord Marrowgar Boss Abilities

Lord Marrowgar: 7,000,000 – 23,700,000 hit points

Bone Storm

8,000-800 damage, depending on how far away you are from Lord Marrowgar. The closer you are, the more damage you’ll take.
Physical damage
3 second cast time
Heroic mode adds a bleed effect

Bone Spike Graveyard

Damages 10 percent of your health per second
Physical damage
Impales any player it hits
Lasts 5 minutes
3 second cast time

Coldflame

6,000-11,000 damage per second
Frost damage
Instant cast
8 yard radius

Saber Lash

200 percent weapon damage
Damage is split between two of your party members.
Hits those within melee range.

Lord Marrowgar Boss Strategy Guide

You’ll need two tanks for the 10-man fight against Lord Marrowgar and maybe even one secondary tank to help soak up some of the damage from Saber Lash. Tanks and Melee DPS should stand as far away as they can while still remaining in his strike zone, which is larger than you might think.
Lord Marrowgar shoots Coldflame across the floor almost non-stop, so you’ll have to keep moving and stay out of the flames.
Periodically, Lord Marrowgar will go into a whirlwind and cast Bone Storm. Run away so you don’t get hit by him. In this pahse tanks should taunt periodically so they keep him away from raid. He gives ample warning before he casts Bone Storm, so you can brace for it. Don’t forget to keep dodging Coldflame in the meantime.
Ranged DPS should switch to the bone spikes whenever Lord Marrowgar casts Bone Spike Graveyard. This will free any party members who become impaled by them. If ranged DPS don’t pick up the bone spikes, whoever’s impaled will die.