Sacred Stone monks are followers of a martial philosophy that seeks to emulate the strength of rock and stone. They don gargoyle masks and use a finely honed sense of touch to measure their surroundings by contact with the ground. They avoid speaking, or extraneous thought for that matter. They live only to test themselves with deprivation and to punish those who doubt the strength of elemental earth.

Earthen Stance

At 3rd level, you have learned how to imbue your stance with the very essence of the elemental plane of earth. As a bonus action, you can spend 1 ki point to enter into this stance for 1 minute. While in this stance, you gain the following benefits:

Honed Touch. You gain tremorsense out to 10ft.

Parrying Block. If a creature you can see hits you with an attack roll,  you can use your reaction to parry and roll a dice, applying a bonus to your AC equal to the number rolled, potentially causing the attack to miss you. The dice rolled is equal to your Martial Arts die.

Stone Step

At 6th level when you use your step of the wind, you have a burrowing speed equal to your walking speed. You can choose to leave behind a tunnel as you go by going at half speed. The tunnel is big enough for creatures of the same size as you to enter without squeezing. 

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Earthpound

At 11th you gain the ability to use the very ground as an offensive weapon. As an action you can strike the ground, and force each creature within a 20 ft radius that is touching the ground to make a Strength saving throw equal to your ki save or take 2d8 bludgeoning damage and fall prone. On a successful save the creature only takes half damage and does not fall prone. This damage is considered magical for the purpose of overcoming immunity and resistance. 

You can increase the strike's damage by spending ki points. Each point you spend, up to a maximum of 3, increases the damage by 2d8. 

Indomitable Endurance

At 17th level, you are so attuned to the elemental plane of earth that it's strength flows through your body and it's movements. You gain the following benefits to your earthen stance:

Improved Touch. While in your earthen stance, your tremorsense extends out to 30ft. 

Stone's Resistance. You gain resistance to bludgeoning, piercing, and slashing damage for the duration of the stance. 

Steelskin. While in your earthen stance you gain a bonus to your unarmored defense equal to your constitution ability score modifier.