From Harry Potter, Avada Kedavra is a spell that causes instant death. The victim's body is completely unmarked, the cause of death is totally unapparent. Avada Kedavra causes a bright green flash of light, and instant death. It cannot be blocked. Only one person in recorded history has ever survived a properly cast Avada Kedavra, Harry Potter. This spell requires a quite experienced wizard or witch to be succesfully cast. Avada Kedavra is one of the Unforgivable Curses.