Chest of the Forlorn Conqueror

Chest of the Forlorn Conqueror is a tier 11 armor token. It can be exchanged at in Stormwind City or  in Orgrimmar for the following items:
 * Mercurial Robes (heroic)
 * Mercurial Vestment (heroic)
 * Reinforced Sapphirium Battleplate (heroic)
 * Reinforced Sapphirium Breastplate (heroic)
 * Reinforced Sapphirium Chestguard (heroic)
 * Shadowflame Robes (heroic)

Source
This item drops from Halfus Wyrmbreaker, Valiona and Theralion, and the Ascendant Council in the Bastion of Twilight on Heroic mode.

It can also be purchased from the following vendors for :
 * in Stormwind City
 * in Orgrimmar