Concussion Attack [Ambush]

Your attacks can damage your opponent’s ability to think clearly.

Prerequisite: Sneak attack +3d6.

Benefit: Your successful sneak attack imposes a –⁠2 penalty on the target’s Intelligence and Wisdom checks, as well as on any Intelligence- and Wisdom-based skill checks, for 10 rounds. If you use this feat a second time on a target before 10 rounds have elapsed, the effect of the first use expires.

Using this feat reduces your sneak attack damage by 2d6.

Source: Complete Scoundrel, page 75.