Terrifying Strike( Drow of the Underdark, p. 54)
Your sneak attacks inspire fear.
Intimidate 4 ranks, Sneak attack +2d6,
The target of your sneak attack is shaken for 1 round. This effect doesn't stack with any other fear effects, including itself. This is a mind-affecting fear effect.Using this feat reduces your sneak attack damage by 1d6.