Draco plays a crucial role in Half-Blood Prince, when Lord Voldemort orders him to murder the Headmaster of Hogwarts, Albus Dumbledore. Like Regulus Black, Draco is infatuated by the Dark Arts and eagerly takes on the task as a chance for glory, of which he seems to get very little. In an effort to prove himself, Draco works alone without the help of his cronies, Crabbe and Goyle, or his favourite professor, Severus Snape. Under his aunt Bellatrix Lestrange's instruction, Draco has become quite proficient in Occlumency, a skill that Harry has never mastered.