Untwisting Iron Strength (Combat)Source Inner Sea Combat pg. 13 (Amazon)
You are a master at breaking through even the toughest of objects, as though your fists were adamantine hammers.
Prerequisites: Str 15, Wis 13, Perfect Style, base attack bonus +9 or monk level 9th.
Benefit: When using Perfect Style, you can ignore an amount of hardness equal to your character level. Additionally, you gain a +4 bonus on Strength checks to break objects. If you spend 1 ki point as a swift action, you also gain the benefits of Improved Sunder for 1 round.Source Weapon Master's Handbook pg. 25 (Amazon)
You can spend 2 stamina points instead of 1 ki point when using Untwisting Iron Strength.