(click for the GIF). Snape not only deflects McGonagall’s attack but uses it to take down Alecto and Amycus in a single armwave behind his visual field. Like they both had their wands out too but BOY they did not see that coming. Snape knew that he needed to get rid of them before being driven out of the castle so that they wouldn’t harm any of the students. Honestly I can't believe I didn't realize he did this.