ATLA Way of the Four Elements

Loosely based upon Avatar the Last Airbender. This subclass seeks to rework the Four Elements Monk, and by "rework," I mean "throw out the vanilla subclass completely and create something that is hopefully more fun." The class revolves around attuning to one or more of the elements each day, with each one giving you different buffs that you can tailor to what you expect to encounter. Of course, if you want to RP a single-element bender like in ATLA, that is also an option.

Elemental Disciplines

When you choose this tradition at 3rd level, you learn mystic disciplines that harness the power of the four elements. Whenever you finish a long rest, choose one of the four elements to attune to. You remain attuned to that element until you chose to attune to a different one after another long rest.

The element you attune to will give you various abilities. You gain these additional abilities at 6th, 11th, and 17th level. 

Elemental Control

Elemental Abilities

• Water: You can cast the shape water cantrip. You can choose to have your Martial Arts attacks deal cold damage.
• Earth:  You can cast the mold earth cantrip. You can choose to have your Martial Arts attacks deal force damage.
• Fire: You can cast the control flames cantrip. You can choose to have your Martial Arts attacks deal fire damage.
  
• Air: You can cast the gust cantrip. You can choose to have your Martial Arts attacks deal thunder damage.

 

Ebb and Flow

Starting at 3rd level, you have learned how to absorb and interact with the raw energy of nature. When you take damage of the type from your attuned element, you may use your reaction to reduce the damage by an amount equal to a roll of your martial arts die + your Wisdom modifier + your monk level. When you use this feature, you regain 1 ki point.

Advanced Elemental Disciplines

Starting at 6th level, your control over the elements has increased to the point that you can use the following abilities based on your attuned element.

• Water - Aquatic Brawler: On your turn, you may spend 1 ki point to coat your limbs with water and give all of your unarmed strikes reach until the start of your next turn. With this reach, you may attempt to grapple a target following the normal rules of grappling. You must continue to keep this ability active by spending ki points in order to maintain the grapple each turn.
• Earth - Immovable: On your turn, while in contact with rock or earthen material (horizontal or vertical) you may spend 1 ki point as a bonus action to root at least two of your limbs to the surface. While rooted, your speed is 0 and you have advantage on saving throws against being grappled or knocked prone. If any enemy comes within your reach during their turn, you may use your reaction to perform an opportunity attack, or spend an additional ki point to use your Flurry of Blows as a reaction instead. This ability lasts for 1 minute, or until you dismiss it as a bonus action on your turn, or until another creature makes a successful Strength (Athletics) check against your ki save DC to uproot you.
• Fire - Burning Fists: When you hit an enemy with an attack from your flurry of blows, the target must make a Constitution save or be burned. While burned they take fire damage equal to one roll of your martial arts die, plus an additional instance of the damage at the start of each of their subsequent turns. The target may repeat the saving throw at the start of each of their turns. On a successful save, the effect ends and/or no damage is dealt.
• Air - Floating Sphere: As an action, you can spend 1 ki point to gain a flying speed equal to half of your movement for 1 minute. Additionally, when you use your Step of the Wind feature, enemies within 5ft of you gain disadvantage on their next attack.

Improved Elemental Control

Starting at 11th level, your mastery of the elements has expanded beyond just one discipline. When you finish a long rest you may attune to two elements instead of just one.

Elemental Redirection

Also starting at 11th level, when you reduce the damage taken from an attuned element using your Ebb and Flow to 0, if the effect that caused the damage was the result of a ranged attack roll or could otherwise reasonably be caught in your hand (given that it deals no damage),  you can spend 1 ki point to make a ranged attack with the element you just absorbed, as part of the same reaction following the same rules as your Deflect Missiles feature. 

Elemental Mastery

Starting at 17th level, you gain access to the following abilities based on your attuned elements.

• Water - Blood Manipulation: Requires Concentration. As an action on your turn, you may spend 3 ki points to attempt to control the water within a target's blood. The target must make a Constitution saving throw. On a failed save, the target is restrained. Creatures composed entirely of water have disadvantage on this saving throw. On subsequent turns, you may use your action to force the target to move along the ground up to 15ft You may also use your bonus action to cause the target to take 2d10 cold damage. A creature restrained by this effect may use an action on their turn to repeat the saving throw, breaking free if they succeed. Ethereal creatures, constructs, or any other creatures that do not have blood are immune to this effect. 
• Earth - Earth Tremor: As an action on your turn, you may spend 3 ki points to strike the ground and send out a violent tremor. All grounded creatures within 20ft of you (counting vertical distance the same as horizontal distance) must make a Dexterity saving throw. On a failed save the creature takes 2d10 bludgeoning damage and is knocked prone. On a successful save, the creature takes half damage. Using this action counts as an attack for the purposes of enabling you to perform an attack with your bonus action.
• Fire - Fiery Presence: While in combat, hostile creatures that start their turn within 5ft of you must succeed on a Dexterity saving throw or take 2d6 fire damage. As an action you may spend 3 ki points to expel fire in a 15ft cone in front of you. Creatures caught in the range must succeed on a saving throw or take 8d6 fire damage, or half as much on a successful save. You may also spend additional ki points when using this ability to increase the damage by 1d6 per point spent. Using this action counts as an attack for the purposes of enabling you to perform an attack with your bonus action.
• Air - Suffocation Sphere: Requires Concentration. As an action you may spend 3 ki points to attempt to forcibly draw the breath out of a creature within 30ft of you. The target must make a Constitution saving throw or take 3d10 damage, or half as much on a successful save. On subsequent turns you may spend an additional ki point to keep the effect active. The target may repeat the saving throw at the start of each of their turns. Every time the target fails the saving throw the damage increases by 1d10. Creatures that do not need to breathe are immune to this effect.