Dark Magic

Dark Magic, also referred to as Black Magic is a powerful form of magic that draws on malvolent powers that asks the caster to tap into dark places of temptation. Such magic has typically been used for dark purposes that deliberately cause harm in some way, e.g. to injure or kill, to cause destruction or misfortune, or for personal gain without regarding the conquences. In popular usage, the term "dark magic" is often used to describe any form of magic that goes against the Forces of Nature. Dark sorcery requires a steep price to be paid in exchange for power. THose will to practice must sacrifice that which they hold most dear.

Description
A "dark witch" refers to any witch or wizard who has tapped into dark magic, either to perform something they were not strong enough to do individually with traditional or other forms of magic or as a means to empower themselves with far greater strength. Despite it's power, dark magic is known to severely corrupt the practitioner by distorting the human perception from between what is right and wrong and most practitioners of dark magic become malefic over the course of time.

Often stated that "Evil isn't born, it's made", Light Magic can turned into dark as when the user has committed a evil act: like when Cora Blackwell ripped out her own her with her dark magic and then never put it back in and bascially became virutally "soulless".