“Dark magic is the manipulation of the powers of darkness, which is not something that most people understand, but that makes it far more dangerous to anyone who tries to use them. Dark magic is a secret, for it is the dark arts, and it is almost impossible to see.” ―Sorcerer’s Apprentice to Harry Potter [src]
The dark magic that one can acquire is the knowledge of how many curses may be used and how to get away from each one. The power required to use these powers is inversely proportional to how many curses are involved in the spell and how powerful they are. Dark magic is most useful to those who want to control or exploit the dark arts through powerful, unpredictable spells.
Known types of dark spells include:
Charms such as Polyjuice Potion, Polyjuice Potion-Grass and Polyjuice Potion-Slug
Dark magicks may also include Dark Arts such as Divination.
Dark magic was said to exist millennia ago, with the Dark Lord of Hogwarts having taught the first Dark magic to his students at Hogwarts School of Witchcraft and Wizardry. However, when he was defeated, Dumbledore had an idea to help the students learn new spells rather than teach them more powerful and dangerous ones that could be abused by other students. To help the students, Dumbledore created the school “The Potter Family House” to create an environment free from the dark arts, and to create a school environment where magic could be taught.
In 1994, when Harry Potter was a student at Hogwarts, he received a message from an unnamed Dark Lord, a professor of Dark Arts within the magical world. The professor’s message was for Harry to find a man named Slughorn in the Department of Mysteries in a secret location. The Dark Lord then instructed Harry to use his new-found “potions” to get what he wanted from Slughorn in order to bring down his new evil mentor, the Voldemort.
At this time, Hogwarts was controlled by Lord Voldemort, and was under his control. In order to break free of Lord Voldemort’s control on the school, Harry had to defeat the Dark Lord in his first attempt. The Dark Lord revealed everything to Harry to be false, but to make things even more dire for Harry, the Dark Lord gave him what he asked. Slughorn was in fact the teacher that helped Harry