Abjuration [Force]
Level: Duskblade 2, Sorcerer 2, Wizard 2
Components: V
Casting Time: 1 immediate action
Range: Personal
Target: You
Duration: 1 round or until discharged
With a word, you evoke a barrier of invisible force.
You project a field of invisible force, creating a short-lived protective barrier. You gain a deflection bonus to your AC equal half your caster level (rounded down) against the next attack made against you before the end of your next turn.
You can cast this spell even when it’s not your turn; however, you must cast it before your opponent makes his attack roll to gain the benefit.
Source: Player’s Handbook II, page 109.