Leggings of the Forlorn Vanquisher

Leggings 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 Leggings
 * Magma Plated Legguards
 * Magma Plated Legplates
 * Stormrider's Leggings
 * Stormrider's Legguards
 * Stormrider's Legwraps
 * Wind Dancer's Legguards

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

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