Ki. The Grandmaster Monk has 18 ki points which it may spend in the following ways:

Stunning Strike. When the Grandmaster Monk hits another creature with an unarmed strike, it may spend 2 ki point to attempt a stunning strike. The target must succeed on a DC 16 Constitution saving throw or be stunned until the end of the Grandmaster Monk's next turn.

Focused Aim. When the Grandmaster Monk misses with an attack roll, it can spend 1 to 3 ki points to increase your attack roll by 2 for each of ki point it spends, potentially turning the miss into a hit.

Quickened Healing. As a bonus action, the Grandmaster Monk can spend 3 ki points and regain a number of hit points equal to 16 (2d10 + 5).

Incorporeal Movement.  As a legendary action the Grandmaster Monk may spend 2 ki points and move up to half its movement speed. This movement does not provoke opportunity attacks and allows the Grandmaster Monk to move through other creatures and objects as if they were difficult terrain. It takes 11 (2d10) force damage if it ends its turn inside an object and is shunted to the closest unoccupied space outside the object. 

Hidden Step.  As a reaction after being hit by an attack the Grandmaster Monk may spend 1 ki point and move up to 10 ft and become invisible until the start of its turn.

Evasion.  When the Grandmaster Monk is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, it instead take no damage if it succeed on the saving throw, and only half damage if it fails.

Multiattack. The Grandmaster Monk makes three unarmed strikes.

Unarmed Strike. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 11 (1d10 + 5) bludgeoning damage. This is a magic weapon attack.

Flurry of Blows. Make two additional Unarmed Strikes

Quickened Healing. As a bonus action, the Grandmaster Monk can spend 3 ki points and regain a number of hit points equal to 16 (2d10 + 5).

Hidden Step.  As a reaction after being hit by an attack the Grandmaster Monk may spend 1 ki point and move up to 10 ft and become invisible until the start of its turn.

Deflect Missles. The Grandmaster monk can use its reaction to deflect or catch a missile when it is hit by a ranged weapon attack. When it does so, the damage it takes from the attack is reduced by 30 (1d10 + 25).

If this reduces the damage to 0, it may as part of the same reaction make a ranged attack with the weapon or piece of ammunition. This attack has a +10 to hit, a +5 to damage and a range of 20/60 ft.

The Grandmaster Monk can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Grandmaster Monk regains spent legendary actions at the start of its turn.

Incorporeal Movement. As a legendary action the Grandmaster Monk may spend 2 ki points and move up to half its movement speed. This movement does not provoke opportunity attacks and allows the Grandmaster Monk to move through other creatures and objects as if they were difficult terrain. It takes 11 (2d10) force damage if it ends its turn inside an object and is shunted to the closest unoccupied space outside the object. 

Rapid Strike. The Grandmaster Monk makes one Unarmed Strike.

Align Ki (3 actions). The Grandmaster Monk regains 3 ki points and may end one effect on it causing it to be charmed or frightened.