Blackrock Spire (BRS) is a dungeon at the upper part of Blackrock Mountain, inhabited by members of the Dark Horde such as orcs, forest trolls, and ogres, as well as their new allies, the Black Dragonflight, who are led by the son of Deathwing-- Nefarian. It consists of two five-player dungeons that cover several precarious floors: Lower Blackrock Spire (LBRS) and Upper Blackrock Spire (UBRS), each with their own set of bosses that players must defeat.