The Left-Hand path is a form of magic often associated with black magic (dark magic), although technically it could be any of the arcane arts black or white used for evil reasons. It opposes the natural order of things, and is more chaotic.
Background[]
Followers of the left-hand path use their magical art for evil.
Many witches are of the dark variety, evil followers of the left-hand path. The three witches of Tamir are such members.
The leaders of the Forty Thieves had once been students of natural order, magic, and philosophy. They soon differed with their teachers, however, over just what constitutes good and evil. Their studies led them down the dark path that equates might with right and gold with good.
The Witch of the Dark Forest followed the dark path, for which there is little doubt.
The dark path often has a strict moral code--although one, of a truly black and perverse type. From the perspective of its followers, their actions are quite moral. For some there is no such thing as good or evil, seeing them as abstractions which do not apply well to life in the real world. They make matters that are by their very nature complex seem rather too simple. It is a dispassionate philosophical discussion.