Crown of the Forlorn Vanquisher

Crown of the Forlorn Vanquisher is a tier 11 armor token. It can be exchanged at in Stormwind City or  in Orgrimmar for the following items:
 * Firelord's Hood
 * Magma Plated Faceguard
 * Magma Plated Helmet
 * Stormrider's Cover
 * Stormrider's Headpiece
 * Stormrider's Helm
 * Wind Dancer's Helmet

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