Water Splitting Stone

 
Prerequisite(s): Improved Unarmed Strike, Stunning Fist, Dex 13+, Wis 13+, Base Attack Bonus 9+.
 
Benefit: You gain a +4 bonus on damage rolls when you make an unarmed strike against an opponent whose damage reduction is effective against your unarmed strikes. This feat's benefit does not apply against a target if its damage reduction does not apply to your attacks. For example, a monk with ki strike (adamantine) does not gain the bonus on damage rolls against a foe with damage reduction that affects attacks with adamantine weapons.
 
Special: A fighter can select Water Splitting Stone as one of his fighter bonus feats. A monk with the Stunning Fist feat can select Water Splitting Stone as long as she has a base attack bonus +9 (other prerequisites can be ignored).
 
Source: PHB II