Blackhand the Destroyer, also known as the Warlord of the Black Horde, and the Unkillable Ork is a massive and powerful Ork warrior who was hand-chosen by the warlock Gul'dan to lead the Black Horde as the Warlord - leader of the entire Orkish military.
Blackhand is a devout follower of Gul'dan. The reason for this being that Gul'dan found the Ork who would become Blackhand as a runt, and cared for the creature. Since Orkish psykers such as Gul'dan are born, not trained, Blackhand could never become like his adopted father, and instead was trained in the pits to become a warrior. Gul'dan taught Blackhand things that the WAAAGH would not, however. Clever tools that would come in extremely handy in the future, when he seized control of the Orkish people during the period of time known as the Great Devastation.
Gul'dan was like a father to Blackhand, and when the orkish warlock rallied the furious inhabitants of Orsinium together under one flag - the flag of the Burning Legion, Blackhand was eager to rise up the food chain along with his adoptive father. This opportunity presented itself when the former Warlord, Krolag, was killed for betraying the warlock Gul'dan. After this, Blackhand offered to take the role of Warlord of the Black Horde, and bring glory to the orks through bloody conquest and faithfulness to the demonic Burning Legion. Gul'dan accepted, and since then, Blackhand has battled on the front lines with his orkish armies, as they carve bloody paths to victory through the Velous nations of planet Earth.
All across Velous, Blackhand's name is feared and dreaded, for he has earned the title of The Destroyer, because to Blackhand, there is no enemy he cannot destroy, no challenge he cannot surmount. No task that will shake his loyalty, and his unfailing ability to kill everything that stands between him and victory, in the name of Gul'dan and the Orks.