Imposing Bearing (Armor Mastery, Combat)Source Armor Master's Handbook pg. 17
Your armor allows you to push your opponents around.
Prerequisites: Poised Bearing, base attack bonus +11 or fighter level 8th, armor training class feature, proficiency with heavy armor.
Benefit: You treat your size as two categories larger for the purposes of determining the size of creatures against which you can attempt bull rush, dragAPG, overrun, and trip combat maneuvers.Source Armor Master's Handbook pg. 20 (Amazon)
You can spend 5 stamina points as a swift action to add half your armor bonus to your next combat maneuver check this turn. Alternatively, you can spend 5 stamina points as an immediate action to add half your armor bonus to your CMD against a single combat maneuver this turn. (See page 17.)