Arcane Shield (Feat)

You can convert any spell into a defense.

Prerequisites: Arcane Caster Level 11

Related: Arcane Insight (Feat)

Benefit: As an immediate action, you can sacrifice a prepared spell or unused spell slot of 2nd level or higher and gain a dodge bonus to AC equal to 1/2 the level of the spell or spell slot you sacrificed (drop fractions). 0th and 1st levels spells cannot be used to trigger this effect. This dodge bonus lasts until the start of your next turn.

Note: This feat lets you use your immediate action at any point prior to damage resolution to attempt to retroactively make a successful attack miss. Obviously, you can also use it before an attack roll.