Combat Expertise( Player's Handbook v.3.5, p. 92)
[Fighter Bonus Feat, General]
You are trained at using your combat skill for defense as well as offense.
Chink in the Armor (SaS) , Cobalt Expertise (MoI) , Combat Cloak Expert (PH2) , Combat Insight (CW) , Defensive Strike (CW) , Deft Strike (CAd) , Epic Combat Expertise (CW) , Improved Disarm (PH) , Improved Feint (PH) , Improved Overrun (SF) , Improved Trip (PH) , Improved Whirlwind Attack (ELH) , Karmic Strike (CW) , Melee Evasion (PH2) , Quick Staff (CW) , Sand Snare (Sa) , Shield of Blades (PE) , Superior Expertise (DD) , Superior Expertise (FP) , Vicious Wound (SS) , Whirlwind Attack (PH) , Improved Combat Expertise (CW) , Deft Strike (Dr) , Sense Weakness (Dr) , Surprising Riposte (DrU) , Deceptive Dodge (DC) , Mighty are Fallen (DC) , Riposte (DC) , Single Blade Style (DC) , Spinning Defense (DC) , Inlindl School (DrU) , Steal And Strike (DrU) , Vae School (DrU) ,
When you use the attack action or the full attack action in melee, you can take a penalty of as much as -5 on your attack roll and add the same number (+5 or less) as a dodge bonus to your Armor Class. This number may not exceed your base attack bonus. The changes to attack rolls and Armor Class last until your next action.
A fighter may select Combat Expertise as one of his fighter bonus feats (see page 38).
A character without the Combat Expertise feat can fight defensively while using the attack or full attack action to take a -4 penalty on attack rolls and gain a +2 dodge bonus to Armor Class.