Throat Punch

Improved Unarmed Strike (PH) , sneak attack +3d6,

Your successful sneak attack delivered with an unarmed strike temporarily hinders the target's ability to speak. For the next 3 rounds, the target takes a -5 penalty on any skill check requiring speech and has a 50% chance of failure when casting a spell with a verbal component or activating a magic item with a command word. Multiple uses of this feat don't increase the duration beyond 3 rounds. Using this feat reduces your sneak attack damage by 2d6.

You must be able to reach your foe's neck to use this feat.

Your successful sneak attack delivered with an unarmed strike temporarily hinders the target’s ability to speak. For the next 3 rounds, the target takes a -5 penalty on any skill check requiring speech and has a 50% chance of failure when casting a spell with a verbal component or activating a magic item with a command word. Multiple uses of this feat don’t increase the duration beyond 3 rounds. Using this feat reduces your sneak attack damage by 2d6.

You must be able to reach your foe’s neck to use this feat.

By making a precise punch to the throat, you can render a target unable to speak effectively.