The rarity of Unbroken Stallion is Mythical, and been equipped it takes a “Bundle” slot. At this moment the item is available for trade.
Unbroken Stallion is a skin for Centaur Warrunner. The skin was added to the game on October 20, 2014, it was created by Nateo.
Unbroken Stallion has been recently added to the game, which makes it rather popular with the game community.