Icecrown Citadel: Lord Marrowgar

After you have passed some annoying, but yet refreshing trash (not like the fast-loot pinata aka ToC), you will face to face with this giant skeleton called Lord Marrowgar.

This fight can be tricky on the start due to some spike damage on 1-3 targets, requires some movement around and a phase with moderate raid damage. But once you get the hang of the incomming damage  and positioning then its a cake.