Avada Kadavra

The Killing Curse (Avada Kedavra) is a tool of the Dark Arts and one of the three Unforgivable Curses. It is one of the most powerful and sinister spells known to wizardkind. When cast successfully on a living person or creature the curse causes instantaneous and painless death, without any signs of violence on the body.

There have only been a few counterspells to the curse. One may dodge the green bolt, block it with a physical barrier, use the jacket of protection or by the use of Priori Incantatem. The Killing Curse is an 'unblockable ' curse, thus shield charms won't defend against it. An explosion or green fire may result if the spell hits something other than a living target or the jacket of protection.