Demon Slayer

Demon slaying monks have mastered breathing techniques that have allowed them to perform different abilities based on the stances they take during battle. Sucking in the air around them, they concentrate on the oxygen circulating their bodies, imbuing it with power and oxygenating every single cell, allowing them to perform magnificent feats. These specific monks have learned the 10 techniques of the water breathing technique and can perform awe inspiring actions that help them defend the innocents from the demons that lurk in the wild.

Total Concentration

You can activate the total concentration breathing technique as an action and spending 1ki point, this lasts 10 minutes and requires your concentration. Whilst maintaining your concentration you gain extra cold damage with your Demonised weapon equal to half your monk level (rounded up) on all attacks. You also reduce the damage of all incoming attacks by 1d4 which increases as you gain levels in this class.  If you take damage whilst maintaining the total concentration ability, you must made a constitution saving throw with a DC of half the damage taken or 10, whatever is higher, if you fail the concentration check the Total Concentration Breathing Technique ends and cannot be used again until 1d4 + 1 (for every level of exhaustion) turns.

At level 6 you reduce incoming damage by 1d6, 1d8 at level 11 and 1d10 at level 17.

Breathing Forms

Breathing forms:  When you take this subclass at level 3 you gain access to 4 breathing forms from the Water breathing stances list, at later levels you gain access to more breathing forms
You cannot use a breathing form unless you have the Total concentration ability active.
You can take a number of stances consecutively equal to your wisdom modifier.

Eighth Form: Waterfall Basin

A downward slash that unleashes the full fury of a waterfall to crash down on an enemy below. By spending 1 ki and taking this stance as a bonus action, on your next attack the target is slammed with a torrent of water and must make a dexterity saving throw, on a failure they take 1d6 cold damage and are knocked prone. You may add an additional 1d6 of cold damage for every additional 2 ki spent.

Fifth Form: The Merciful Rain of a Dry Day

A "sword strike of kindness" that kills the target with little to no pain. Used when the enemy surrenders. By spending 2 ki and taking this stance as a bonus action, when you attack an incapacitated or willing enemy and hit, you deal critical damage and if the target falls to 0hp it dies instantly, making no death saving throws as it is decapitated, feeling no pain.

First Form: Water Surface Slice

The swordsman generates enough momentum to create a powerful single concentrated slash. By spending 1 ki and taking this stance as a bonus action. On your next attack you roll the same damage die as your weapon the result being the additional cold damage you deal on a hit. You may also add an additional die of cold damage for each additional 2 ki spent.

Fourth Form: Striking Tide

The swordsman makes multiple consecutive slashes while twisting their body in a flowing fashion similar to a harsh tide. By spending 2 ki and taking this stance as a bonus action, the next 2 attacks made with your demonised weapon can also target another enemy within 5 feet of the target.

Ninth Form: Water Splash

Minimizes the landing time and surface needed when landing, allowing the user to move without limits. Ideal when fighting in a place with no solid foothold. By spending 1 ki and taking this stance as a bonus action, the user ignores difficult terrain and can move walk and jump on air as if it was solid ground.

Second Form: Water Wheel

The swordsman leaps and spins in the air while releasing an flowing attack in a circular motion. By spending 2 ki, you use your action to spin in a circular motion around you, every creature within 5 feet of you must make a Dexterity saving throw or take your regular weapon damage.

Seventh Form: Piercing Rain Drop

A fast and accurate stab. The fastest Breath of Water technique. By spending 1 ki and taking this stance as a bonus action, you gain advantage on your next attack and it scores a critical hit on a 19 or 20. This ability can also be used when you take your reaction to make an opportunity attack but costs 3 ki to use.

Sixth Form: Twisting Whirlpool

The swordsman fiercely twists his upper and lower body, creating a whirlpool that cuts anything caught in it. By spending 1 ki you use your action to create a vortex of water in a 15ft radius around, each creature within the vortex must make a Dexterity saving throw taking 3d6 cold damage on a fail and half on a success. A creature that fails is also launched 20ft in a random direction. This ability can only be used underwater.

Tenth Form: The Dragon of Change

A continuous attack that increases in power with each rotation, creating a strong slash. By spending 3 ki and taking this stance as a bonus action, when you hit a creature with an attack with your demonised weapon it counts towards your consecutive hits. Your attacks deal an extra 1d6 damage for each attack that hit before it whilst this stance was active. The effect ends once you miss an attack.

Third Form: Dance of the Rapid Current

The swordsman swings his blade at his opponent in a way that mimics the movement of waves on the surface of water. By spending 1 ki and taking this stance as a bonus action, your attacks made with your demonised weapon gain advantage on all attacks until the end of your next turn.

Demonised Weapon

When you gain this ability, you choose one weapon to become your demonised weapon, this weapon must be used when attacking with your breathing forms. If you lose or break your demonised weapon, you can spend a long rest and 50gp to make a new weapon your demonised weapon.

Demonite magic

The demonite that infuses your weapon during your ritual evolves along with its wielder. At this stage it infuses its self with magic allowing the wielder to bypass demons magic resistance.

Demonite Awareness

Your demonised weapon changes appearance when in the presence of different entities. When an undead, demon or devil is within 30ft of you, your demonised weapon changes colour, black for undead, purple for demons and red for devils.

Top Form

You gain access to the 11th breathing form, the hardest to master of all water breathing techniques.

Eleventh Form: Lull

By spending 5 ki as an action the swordsman ceases any body movements and engages a skill that disables and nullifies incoming attacks. However, its effectiveness is limited as fast and numerous attacks can break through. If the monk is hit with 5 attacks within a single round the condition ends.