Way of Boulder

As ancient as the mountains themselves, this Tradition has been passed down from master to student since the earliest days of civilization. Building their monasteries on mountain peaks and deep in subterranean caverns, monks who pursue this Tradition focus on becoming as large and immovable as the mountains that surround them. They grow in girth and size, and use their weight to rain down devastating blows.

As a follower of the Way of the Boulder, you strive to be as immovable as the bedrock of the world, as imposing as a mountain's peak, and as fruitful as fertile soil. Boulder monks are stubborn and inflexible, but their loyalty is unshakable.

Solid Body

When you adopt this Tradition at 3rd level, you can use your physical bulk to enhance your offense and defense. When not wearing armor or a shield, your Armor Class is equal to 10 + your Constitution modifier + your Wisdom modifier.

You can also use your Constitution, in place of Strength or Dexterity, for your attack and damage rolls for your unarmed strikes and your melee monk weapon attacks.

Strength of the Moountain

Also at 3rd level, you can use your ki to draw upon the earth below to reinforce your robust frame. As a reaction when you make a Strength ability check or Strength saving throw, you can grant yourself advantage on the roll.

You can use this reaction a number of times equal to your Constitution modifier (minimum of once), and you regain all expended uses when you finish a long rest. If you have no uses available, you can spend 1 ki point to use this reaction.

Rebounding Defense

Starting at 6th level, you can use your massive body to absorb and reflect all but the most powerful attacks. As a reaction when you are hit by a melee weapon attack, you can expend 1 ki point to reduce the damage by an amount equal to 1d12 + your Constitution modifier (minimum of 1) + your monk level.

If you reduce the damage of the triggering attack to 0, you can rebound the blow off your great girth back at the attacker, making a melee weapon attack against the attacker, as part of your reaction. You make this attack with proficiency, and the rebounded attack counts as a monk weapon for the purposes of this special reaction attack.

Ki-Infused Bulk

Beginning at 11th level, your dense, ki-infused, physical form allows you to resist both physical and elemental assaults. At the end of each short or long rest, choose one of the following damage types: bludgeoning, piercing, slashing, acid, cold, fire, lighting, or thunder. You are resistant to that type of damage until the end of your next short or long rest.

As a bonus action, you can pend 2 ki points to realign your ki and switch the damage resistance you gained from this ability to another damage resistance from the list above.

Mighty Form

Upon reaching 17th level, your body surpasses the normal mortal limits of density and mass. Both your Constitution score, and maximum Constitution score, increase by 2.

Earthshaker

Starting at 17th level, you can use your supernatural density to shake the earth. As an action, you can expend 3 ki points to crush the earth beneath you, forcing creatures of your choice within 15 feet to make a Strength saving throw, DC being 10+Constitution modifier. On a failure, creatures take 2d10 bludgeoning damage and fall prone. On a success, they take half damage and remain upright. The ground in this 15-foot radius becomes difficult terrain.

When you use this feature, you can expend additional ki points, increasing the damage of your stomp by 1d10 for each additional ki point you spend, to a maximum of 10d10.