Green Trophy Tabard of the Illidari

Green Trophy Tabard of the Illidari is one of two possible tabard rewards after completing the.

Source
Along with the purple one, the Green Trophy Tabard of the Illidari is given by A'dal in the, a small chest you receive in addition to the quest reward. It randomly chooses the green or purple tabards.

This tabard may be discarded and reacquired at a tabard vendor. One may choose the other color at this time.