The "black arts" are occult practices or magic believed to harness dark, harmful powers. The term also describes secretive, manipulative skills used to deceive or control others.
In another life, before taking the veil of journalistic purity, I practiced the black arts of a political operative, including 'debate prep.' Jeff Greenfield
Visit the Navy-Yard, and behold a marine, such a man as an American government can make, or such as it can make a man with its black arts -- a mere shadow and reminiscence of humanity, a man laid out alive and standing, and already, as one may say, buried under arms with funeral accompaniments. Henry David Thoreau