The material below is Open Game Content from a 3PP Source
Improved Sunder (Combat)
You are skilled at damaging your foes' weapons and armor.
Prerequisite: Str 13, Power Attack, base attack bonus +1.
Benefit: You do not provoke an attack of opportunity when performing a sunder combat maneuver. In addition, you receive a +2 bonus on checks made to sunder an item. You also receive a +2 bonus to your Combat Maneuver Defense whenever an opponent tries to sunder your gear.
Normal: You provoke an attack of opportunity when performing a sunder combat maneuver.
The material below is Open Game Content from the System Reference Document.
IMPROVED SUNDER [Combat]
Prerequisites: Str 13, Power Attack.
Benefit: When you strike at an object held or carried by an opponent (such as a weapon or shield), you do not provoke an attack of opportunity.
You also gain a +4 bonus on any attack roll made to attack an object held or carried by another character.
Normal: Without this feat, you provoke an attack of opportunity when you strike at an object held or carried by another character.
Special: A fighter may select Improved Sunder as one of his fighter bonus feats.
