Greatcloak of the Turned Champion

Source
This item can be found inside the Deathbringer's Cache after defeating Deathbringer Saurfang in the 25-man version of Icecrown Citadel.

Trivia

 * The name of this cloak is in reference to Saurfang's appearance in Ulduar, as the Turned Champion seen during the battle with Yogg-Saron.