Becareful of the Dark Arts...if you betray the dark lord once he will forgive you...but the second time you might not be so lucky..

The Unforgivable Curses
The Unforgivable Curses are three curses: the Killing Curse, the Cruciatus Curse, and the Imperius Curse. The use of any of these curses on another human being is enough to earn a life sentence in Azkaban.

Curse: The Killing Curse
Incantation: Avada Kedavra
Description: This is the worst curse of the three Unforgivable Curses. This curse causes instant death. There is no counter curse to the Killing Curse. The only one to survive the Killing Curse is Harry Potter.

Curse: The Cruciatus Curse
Incantation: Crucio
Description: The Cruciatus Curse causes pain. This curse was popular during the reign of Voldemort.

Curse: The Imperius Curse
Incantation: Imperio
Description: The Imperius Curse gives the caster full control over the one the curse is being used on.

Dark Wizards
Wizard: Grindlewald
Description: There is not much known about Grindlewald. All that is known is that he was defeated by Dumbledore in 1945.