The rarity of Relentless Warbringer is Rare, and been equipped it takes a “Bundle” slot. At this moment the item is available for trade.
Relentless Warbringer is a skin for Centaur Warrunner. The skin was added to the game on May 1, 2014, it was created by Futushia.
Relentless Warbringer has been recently added to the game, which makes it rather popular with the game community.