Monks who follow the Way of the Binding Chain have relentlessly studied the mechanics of how creatures move and use this knowledge to attack their opponents, employing an extensive arsenal of joint locks, pressure points, and other anatomical weaknesses to lock down their enemies while they rain additional blows down on their hapless opponent.

Grappling Techniques

Your mastery of grappling techniques makes them more difficult to escape. You may choose to contest a grappled creature's escape roll using either a Strength (Athletics) or Dexterity (Acrobatics) check, and may choose whether that creature uses its Strength (Athletics) or Dexterity (Acrobatics) check to escape. In addition, your specialized knowledge means if your roll is lower than your Ki save DC, you may instead treat it as equal to your Ki save DC. Finally, your grapples apply the Restrained condition, in addition to the Grappled condition.

Your training also enables you to more easily escape situations where your movement is restricted. As a bonus action, you may spend 1 Ki point to automatically escape from nonmagical restraints, such as manacles or a creature that has you grappled, or to gain advantage on a saving throw or skill check made to escape a magical effect which is physically restraining you.

Your Deflect Missiles ability evolves to function against melee attacks instead of missile attacks. When used, it only reduces slashing, bludgeoning, or piercing damage. If you reduce the physical damage of a melee attack to zero, you may spend 1 Ki point to make a Grapple check against the attacker as part of your reaction.

Crushing Grapple

At 6th level, you learn how to more effectively apply leverage against your grappled opponents. Each turn, when a creature chooses not to use its action to attempt to escape your grapple, or fails an escape attempt, it takes damage equal to one roll of your Martial Arts die, plus either your Strength or Dexterity modifier. In addition, any creature grappled by you takes a −2 penalty to AC and Dexterity saving throws, and it can't use reactions. On its turn, it can use either an action or a bonus action, not both. Regardless of the creature's abilities or magic items, it can't make more than one melee or ranged attack during its turn.

Joint Locks

Beginning at 11th level, while grappling a creature, if you are the target of an attack or a spell effect which allows you to make a Dexterity saving throw for half damage, you may use your reaction and spend 1 Ki point to gain a +5 bonus to your AC or Dexterity saving throw.

If the attack misses, but you would normally have been hit by it without the benefit of the increased AC or saving throw, the attack instead hits the creature you have grappled (which may make a Dexterity saving throw for half damage, if applicable), and you take no damage, interposing the grappled creature between yourself and the source of the effect.

Pressure Points

At 17th level, you learn to target anatomical weaknesses in your opponents to maximize your effectiveness. You may now grapple two creatures simultaneously. In addition, when you hit a creature with an unarmed strike or deal damage with your Crushing Grapple feature, you may spend up to 5 Ki points to channel your Ki into the creature. This creature must make a Constitution saving throw, taking 2d10 force damage per Ki point spent on a failure, or half on a success. On a failed saving throw, the creature has disadvantage on all rolls until the end of its next turn. If the creature is grappled, it is also stunned until the end of its next turn, as pain courses through its body.