If a prot pally can get access to this helm, he can stack 260 block rating and 401 defense rating that buffs their block chance to 45.53% (without holy shield or reckoning of course) and their block value to 803, while still retain 62.35% AC mitigation vs lvl 73 mobs and 18467 HP.

can't wait to see that pally farming heroic instances.  lol