From:
http://www.wow.com/2009/12/18/ready-check-lord-marrowgar/

So, the final summary of fighting Lord Marrowgar is pretty simple. Don't stand in the fire. When he whirlwinds, avoid it if you can, but don't lose your head trying to dodge it. When Bone Spike Graveyard happens, free your raid members as quickly as possible. Make sure you have two tanks soaking the Saber Lash.

The most difficult part of this fight, again, is fighting the urge to completely scatter while trying to avoid the Bonestorm.

Ok, so after reading thru that I have a better understanding of what is going on. We are not staying together during that whirlwind..and we are not getting the person off of the spike quickley enough. So should all dps make a macro for /tar Bone (or whatever its called) and then as a group we focus on staying all together? I am willing to try. I believe if everyone really reads thru this it will make more sense and we will have him down in no time

Ya after watching Tank Spots vid of the fight its an easy fight I think. Just have to pay attention to your surroundings and whats going on. And, get people out of Bone Graveyard when it happens. Don't think grouping up is a good idea though. Frost flame doesn't do that much damage by itself if you don't stand in it for long but, combine its increase during Whirlwind and you could lose alot of people if dps and heals are all in one place. Also, for melee dps he has a huge hit box like Ony so you dont have to be right up on him.

O.K. After last nights run I retract my last statement about standing as a group with the exception that everyone, except the tanks, needs to be standing in the red circle underneath LM. We did ok. But I now think, as someone stated last night, that we need more melee dps on the Bone Spikes and his boney ass.