"Empty your mind.

Be formless, shapeless, like water.

You put water into a cup, it becomes the cup.

You put water into a bottle, it becomes the bottle.

You put it into a teapot, it becomes the teapot.

Now water can flow or it can crash.

Be water, my friend"

 

The Monastery of the Drowned lies deep in the Anauroch desert, built around a constant but meager spring. There, the harsh pragmatics of survival in the barren desert meet the sacred and fragile peace afforded by the spring--for the spring produces barely enough water to sustain the monastery, necessitating a strict rationing. Monks at the monastery meditate for hours a day on the gurgling waters of the spring as the dessert sun scours their tissue of its little moisture, equally soothed by the spring's presence as they are tortured by its proximity. From struggling to exist in this rare dichotomy, the monks have developed a unique philosophy and martial style embodying both the patient meditation of the spring and ruthless efficiency of the desert. 

The central tenet of this martial philosophy is to be like the waters of the spring. Flowing formless and shapeless until a crack is found in the opponent's defense--a mistake, perhaps just an instant of hesitation--and then crashing through it with all the ruthlessness and efficiency. 

In their final ordeal, monks of the monastery meditate for two days around the spring neither eating food nor drinking water. When they are thoroughly dehydrated and on the cusp of death, they are held face down in the shallow water of the spring until they drown. Their bodies are then heaved out and beat once across the diaphragm with a stone rod. If they cough out the spring water, they return to life as Masters of the Way of the Drowned--embodiments of the waters that inspired and tortured them; sustained and destroyed.

Martial Style

Starting when you choose this tradition at the 3rd level, you begin to embody the sacred waters of the spring, formlessly following the path of least resistance, patiently waiting for your opponent to make a mistake, before ruthlessly crashing against them. You gain the following features:

Ebb

If you took the disengage action on your last turn, you may use a reaction to make 1 attack against a hostile creature when it enters your reach. 

 

Flow

If you took the dodge action on your last turn, you may use a reaction to make 1 attack against a hostile creature when it misses an attack against you.

 

Crash

When you hit an enemy with an attack when it is not your turn, you have advantage on all subsequent attacks against that enemy until the end of your next turn. Additionally, these attacks critically strike on a roll of 19 or 20.

Splash

Additionally, you gain access to the following ki feature:

At any time, you may spend 1 ki point to gain an additional reaction for the round.

 

Fount

At 6th level, you are able to emulate the spring further, entering a state of meditative flow even in combat. As an action you may activate this feature. You immediately regain expended ki points equal to your monk level divided by 6 (rounded down) and temporary hit points equal to 2 times your monk level. While this effect is active, you regain the same number of ki points at the start of each of your subsequent turns. This effect can last indefinitely, but the following factors can prematurely remove you from your meditation:

• Taking Damage. Whenever you take damage while this feature is active, you must make a wisdom saving throw to maintain your meditation. The DC equals 10 or half the damage you take, whichever number is higher. If you take damage from multiple sources, such as an arrow and a dragon’s breath, you make a separate saving throw for each source of damage.
• Attacking. Recklessly attacking is incongruous with this reactive, meditative state. If you take the attack action on your turn, the meditation ends immediately. Note: attacks not taken as part of the attack action, like those taken in a bonus action or reaction, do not end your meditation.
• Being Incapacitated or Killed.

You may use this feature once and regain the ability to do so after a long rest.

Swell

Additionally, you gain access to the ki feature Swell:

When you take the Ready action on your turn to ready an attack, you may spend 1 ki point to make that attack disrupting. When that attack is triggered, and if it hits, the target has disadvantage on all its attacks until the start of its next turn.

Flood

Beginning at the 11th level, you learn to emulate the formless nature of water with your attacks. Any time you make an attack, you may spend any even number of ki points to make that attack target 1 additional creature in range for every 2 ki points spent.

Ripple

At the 17th level, you discover how water is able to carry and redirect energy. When you would take damage from an attack, you may use a reaction and spend 3-10 ki points to make 1 melee attack against a creature. If you hit, roll 2 d10 for each ki point spent in activating this ability, and take as the result the lower between the sum of these rolls and the amount of damage you would take. Apply that result to the attack you made as additional bludgeoning damage and, in addition, you take that much less damage from the triggering attack.