In mysticism, black magic or dark magic was the supernatural use of magic for the purposes of evil, often associated with witchcraft.
When the 19th century holographic prostitute acquaintance of James Moriarty witnessed Geordi La Forge and Data access the holodeck's "arch", then watched it disappear, she exclaimed that "It's dark magic, Moriarty!" (TNG: "Elementary, Dear Data")
According to the lyrics from the 20th century Human song, "That Old Black Magic", one who uses "that old black magic" had the ability to put another "in its spell", forcing them to lose their ability to control themselves. (VOY: "The Killing Game", "Virtuoso")