Merciful Strike

(Complete Scoundrel, page 79, DnD 3.5)

[Ambush]

You can strike a creature's vital areas without killing it.

Benefit

Your successful sneak attack deals nonlethal damage. When using this feat, you can ignore the usual -4 penalty on attack rolls for attempting to deal nonlethal damage with a lethal weapon. Using this feat reduces your sneak attack damage by 1d6.