Crown of the Forlorn Conqueror

Crown 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 Cowl
 * Mercurial Hood
 * Reinforced Sapphirium Faceguard
 * Reinforced Sapphirium Headguard
 * Reinforced Sapphirium Helmet
 * Shadowflame Hood

Source
This item drops from Nefarian in Blackwing Descent on Heroic mode.

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