Death Battle2010

Wizard:
Harry is also experienced in curses. He destroys objects with Reducto, slashes enemies with Sectumsempra, and controls minds with Imperius.

Boomstick:
And then there's the Killing Curse... abracadabra.

Wizard:
Avada Kedavra.

Boomstick:
Oh. That magician wasn't trying to kill me. I guess I should probably go apologize to his family.

Wizard:
While Harry's never used the Killing Curse, it is implied that he can. It is an instant kill and unblockable.

Boomstick:
Unless it hits a wall... or a sword... or anything, really.

Wizard:
Almost all magic requires a line of sight and eye contact to perform. The Killing Curse is no exception.