Animate armor.

As Dumbledore demonstrates in Order of the Phoenix, any spell, even Avada Kadavra, can be blocked by a temporarily animate statue (the spell "kills" the statue instead). Which actually annoyed me when I read it, since that implies wizards could imbue each layer of their clothing with intelligence before a battle, and gain a bunch of extra lives.

(Having your breastplate shout taunts at your enemy also frees you up to focus on fighting.)