The unyielding mountain stance focuses on endurance and defense.
While in this stance, you gain a +2 insight bonus to Constitution and Combat Maneuver Defense, and your class AC bonus increases by +2. However, you also suffer a -2 penalty to Dexterity, and your speed is reduced by 1/3, rounded to the nearest 5-ft. increment (20 ft. if your normal speed is 30 feet or 15 ft. if your normal speed is 20 feet).
Adept Mountain Stance
At adept level, the bonus to Constitution, CMD, and AC increases to +3. The penalties are unchanged.
Master Mountain Stance
In its master form, the bonus granted to Constitution, CMD, and AC increases to +4.
Grandmaster Mountain Stance
When you become a grand master this stance, the bonus granted to Constitution, CMD, and AC increases to +5.