Well after 27 deaths I was finally able to kill Marrowgar. I would like to thank Theradin and Mercuio for their help and strats on getting him down.

Here was my strat for anyone looking for ideas to take him down.

I used 3 healers 2 priests and 1 druid. In my early attempts I was using only 2 healers and micro managing my heals. Instead this time I went with 3 healers and made click macros for the healers that would keep up renew and pw shield on the tanks, circle of healing and PoM on every cool down. Then for the druid I did wild growth on every CD and then had a macro that cycled through the raid and cast rejuv and lifebloom.

After setting this up the only healing i had to manage was a few greater / flash heals on the tanks and spamming holly nova during bone storm.

I had everyone follow my tank and run in and parked everyone in the red circle under Marrowgrar. had one button that /target bone and then fast dps spell on each caster to take the bone spikes out.