Sneak Attack

If a character can catch an opponent when he is unable to defend himself effectively from her attack, she can strike a vital spot for extra damage. The character's attack deals extra damage anytime her target would be denied a Dexterity bonus to AC (whether the target actually has a Dexterity bonus or not), or when the character flanks her target. This extra damage is 1d6 and increases by 1d6 at later levels. This additional damage is precision damage and is not multiplied on a critical hit. The character must be able to see the target well enough to pick out a vital spot and must be able to reach such a spot.

Sneak Attack — Kingmaker