Circle of Protection

Close-quarters spell
Quick action to cast

Choose a defense: AC, PD, or MD. For the rest of the battle while you are conscious, you and each ally near you gains a +1 bonus to that defense. Each enemy that misses you or one of your nearby allies with an attack against the defense you chose is hampered until the end of its next turn.

9th Level Spell: 
Attacks against the chosen defense cannot score critical hits.
Epic Feat: 

The spell is now (recharge 16+) after battle instead of daily.