Patch 1.6.0: Assault on Blackwing Lair is a content patch for World of Warcraft that released on 12 July 2005. Among other changes, it featured the release of the Blackwing Lair raid instance, the introduction of the Darkmoon Faire to Azeroth, Battlemasters in major cities, and revamps of the Warlock and Warrior talent trees.
Deep within the fiery heart of Blackrock Mountain, the black dragon Nefarian conducted twisted experiments with the blood of other dragonflights. Intent on seizing the entire region for his own, he marshaled the remaining Dark Horde, a rogue army that embraced the demonic bloodlust of the old Horde. These corrupt orcs, trolls and other races battled against the Firelord Ragnaros and the shadowy Dark Iron dwarves for control of the smoldering mountain. Before he was vanquished by fearless heroes, Nefarian created the twisted chromatic dragons and a legion of other aberrations in his bid to form an army powerful enough to control Azeroth and continue the legacy of his infamous father, Deathwing the Destroyer.