Now that the Warcraft movie is almost here, Blizzard is equipping heroes of the Alliance and Horde with a set of movie-inspired transmogs. Starting today ending on August 1, anyone who logs in will receive a special commemorative cosmetic gear that will be permanently added to your collection.
Only characters of the associated faction can use these items, each set is sent to the first Horde and Alliance character you log in with. A pity Alliance warlocks can't get the Gul'dan Staff! Note that if you for some reason do a faction reroll, the respective faction transmogs will be replaced in the transmog collection with their opposing faction's counterparts.
The Warcraft movie is hitting theaters starting June 9, 2016, depending on your country. Just have a look here.