Monks of the Way of the Boulder gorge themselves on food and drink in order to maximize their weight, but ensure that they still train hard enough to maintain their agility in combat. A monk of the Way of the Boulder is a frightening sight on the battlefield, as he or she can choose to either act as a stalwart barrier against assault or make use of their sheer mass to plunge into enemies. The Way of the Boulder teaches its followers that though life is debilitating, one only needs the power of the mind and the resilience of the body to weather the challenges it brings. 

Low Center of Balance

When you choose this Monastic Tradition at 3rd level, your immense size and weight make it difficult for you to lose your balance. You have advantage on Strength and Dexterity Saving throws made to resist being knocked prone.

Earth Shaker

Additionally when you choose this Monastic Tradition at 3rd level, you have learned to effectively control your remarkable weight and utilize it in combat. When you make an Attack action with an unarmed strike or a monk weapon on your turn, you can spend a ki point to use a powerful stomp attack as a bonus action. All creatures that are on the ground within 10 feet of you must succeed on a Dexterity saving throw against your ki DC or take bludgeoning damage equal to one roll on your martial arts die and be knocked prone. A creature that succeeds on the saving throw talks half as much damage and is not knocked prone.

When you reach 11th level, the range of the stomp increases to a 20-foot radius.

Subsistence

At 6th level, your stored fat makes it easier for you to sustain yourself. To avoid suffering from starvation, you need only eat a half a pound of food every day, and can make food last longer by eating quarter rations. Eating only a quarter of a pound of food a day counts as a quarter of a day without food, as described on page 185 of the Player's Handbook.

Bone Crusher

Also at 6th level, you have continued to train in the mastery of using your size and weight as a weapon. When you move at least 15 feet in a straight line on your turn, you can spend 2 ki points and use your Action to make a rolling attack, continuing to move in a straight line that is 5 feet wide and up to your remaining movement in length. Any creature caught in your path must make a Strength or Dexterity saving throw (its choice) against your ki DC. On a failed save, a creature takes bludgeoning damage equal to two rolls on your martial arts die and is knocked prone in its space. On a successful save, a creature takes half as much damage, and chooses an unoccupied space within 5 feet of itself to relocate to without being knocked prone. If no such space exists, it stays in its own space without being knocked prone.

Willful Endurance

Beginning at 11th level, your will power is so great that you can command your body to keep fighting. As a bonus action on your turn, you can expend a ki point to regain a number of hit points equal to your Constitution modifier. You can expend up to two additional ki points in the same bonus action, gaining an additional amount of hit points equal to your Constitution modifier for each additional ki point expended. 

Master of Mass

At 17th level, you become a pinnacle of will and endurance. Your Constitution score increases by 2, as does your maximum for this score. Additionally, as a bonus action on your turn, you can expend 4 ki points to enter a Boulder Stance, gaining the following changes:

• Your movement speed becomes 0, and you can't benefit from any bonus to your speed.
• You are immune to being knocked prone, and enemies have disadvantage on saving throws on effects that you create that would cause them to be knocked prone.
• You have resistance to nonmagical bludgeoning, piercing, and slashing damage.
• You may use your Stunning Strike ability without spending a ki point once per turn.

You remain in your Boulder Stance for one minute or until you use a bonus action to end it. Once you have entered this stance, you may not do so again until you finish a short or long rest.