While imprisoned on the Material Plane, the Dao, Osmia, sought power. She collected earth around her until her domain sat upon the highest peak of the tallest mountain, Mt. Os. She make the interior of this enormous structure her labyrinthian palace. Those who worshiped her as a goddess were granted bodies like stone. Those who trained to harness their internal energy learned to harden their bodies as diamonds. A few remain with Osmia in service, but some who escaped her prison palace formed the Temple to the Mountain, where the original practitioners, long dead, passed down the secret of using ki to block damage.

Monks of this order take their training to the extreme. The more muscle they add, the more their ki can reinforce. A master of the Way of the Mountain can shrug off ballistae and cannon fire. Sword blades break against their necks, and their punches can tunnel through hills. Their ki is not developed to improve their martial prowess, it is there to make them immovable objects ready to face unstoppable forces.

Hardened Dedication

-Your Martial Arts class feature can no longer be used for Dexterity, monk weapons with the Finesse property and your unarmed strikes use Strength instead.

-When applying your Unarmored Defense, your AC is equal to 10+Strength Modifier+Wisdom Modifier. Your ki defends your body from attacks more effectively than your own agility.

-When applying the Deflect Missiles skill, the damaged reduced is 1d12+STR+your monk level. You are no longer able to expend ki to throw the missile back. Instead, you can spend 1 ki point to add an additional 1d6 to the damage reduction. When ki is spent this way, damage from ranged spell attacks can be reduced.

Boulder Fall

Your ki can accelerate instead of slow your descent. This has explosive consequences.

You can elect not to benefit from your Slow Fall skill, and instead land powerfully enough to shake the ground around you.

When you take falling damage and decline Slow Fall, you become resistant to falling damage until the end of your turn. In addition: any enemy you land on takes 2d6+STR for every 10 ft. you fell, to a maximum of 20d6.

If you land on the ground, all creatures within a 10 ft. radius must succeed on a Strength Saving Throw against your Ki Save DC. On a failure, they take 1d6 force damage for every 10 ft. fallen and are knocked prone as a shockwave of ki radiates out from the impact. On a success, they take half as much damage and are not knocked prone.

Earth Stance

You overload your muscles with ki and increase your size. Starting at 6th level, you can spend 2 ki points to cast the "enlarge" version of the enlarge/reduce spell on yourself for up to 1 minute without requiring concentration. You can use this feature a number of times equal to your Wisdom modifier (min. 1 time).

At 14th level, you can spend an additional 4 ki points and grow up to 2 size categories larger when using this skill. When used this way, your speed becomes 0, you gain an additional 5 ft. reach on all attacks, and your weapon and unarmed strikes do an additional 1d4+your Martial Arts die of damage (as opposed to 1d4 from the enlarge/reduce spell).

One With the Land

You can channel your ki into the ground to sense threats from all sides. Starting at 11th level, you can use an action to spend 4 ki points. Doing so will grant you Tremorsense for 1 hour up to 60 ft.

Diamond Body

Your mastery of ki has molded your body into a living fortress. Starting at 17th level, you are immune to non-magical bludgeoning, slashing, and piercing damage from weapons that aren't adamantine. 

In addition, your unarmed strikes deal double damage to structures and objects.