Intense Blows (Armor Mastery, Combat)Source Armor Master's Handbook pg. 17
Your forceful blows and your armor’s weight make you more difficult to hinder in combat.
Prerequisites: Str 13, Power Attack, base attack bonus +6 or fighter level 4th, armor training class feature, proficiency with heavy armor.
Benefit: When you are using Power Attack, you gain a +1 bonus to your CMD until the beginning of your next turn. When your base attack bonus reaches +4, and every 4 points thereafter, this bonus increases by another 1.Source Armor Master's Handbook pg. 21 (Amazon)
You can spend 5 stamina points to double this feat’s bonus to your CMD for one combat maneuver check. (See page 17.)