Avada Kedavra

Avada Kedavra is the Killing Curse, one of the three Unforgivable Curses. It causes instant death, leaves no mark the books describe as a wound, and cannot be blocked by a shield charm in any scene they show. A rebounded Killing Curse destroyed Voldemort’s body when he attacked the infant Harry. The incantation itself is first taught in a Defence class in the fourth year.