Impeding Attack [Ambush]

Your strikes render your target temporarily clumsy and awkward.

Prerequisite: Sneak attack +4d6.

Benefit: Your successful sneak attack imposes a –⁠2 penalty on the target’s Strength and Dexterity checks, as well as on any Strength- and Dexterity-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 3d6.

Source: Complete Scoundrel, page 78.