Divination
Level: Assassin 3, Mystic Ranger 3, Paladin 3, Ranger 3
Components: V
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 1 round/level
You speak the words of this spell, and a blue mark that only you can see appears on your opponent, highlighting a weak spot in her defence.
You gain the ability to perceive weak points in your opponent’s armour. Your first melee or ranged attack each round is resolved as a touch attack, disregarding the subject’s armour, shield and natural armour bonuses (including any enhancement bonuses) to Armour Class. Other AC bonuses, such as dodge bonuses, deflection bonuses and luck bonuses, still apply.
Source: Spell Compendium (Page 91)