Constant Guardian( Drow of the Underdark, p. 47)
[Fighter Bonus Feat, General]
By paying careful attention to nearby allies and reducing the accuracy of your attacks, you help protect your companions.
Dutiful Guardian (DrU) ,
Once during your turn as a free action, you can take a —2 penalty on your attack rolls to grant a single ally within 10 feet a +2 dodge bonus to Armor Class. This effect lasts until the start of your next turn or until you are more than 10 feet from the chosen ally, whichever comes first.
A fighter can select Constant Guardian as a fighter bonus feat.