Chest of the Forlorn Vanquisher

Chest of the Forlorn Vanquisher is a tier 11 armor token. It can be exchanged at in Stormwind City or  in Orgrimmar along with the appropriate normal version tier piece for the following items:
 * Firelord's Robes (heroic)
 * Magma Plated Battleplate (heroic)
 * Magma Plated Chestguard (heroic)
 * Stormrider's Raiment (heroic)
 * Stormrider's Robes (heroic)
 * Stormrider's Vestment (heroic)
 * Wind Dancer's Tunic (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