Avatar monks are rare to find, because their abilities are mysterious, given by birth and only rarely get discovered with dedication and training. Their abilities are not magic in nature but come from a deeper understanding and connection to the elements, similar to that of elementals. That could be the reason why avatars tend to be of the genasi race. Legends say avatars are always destined to bring great change and are guided by mysterious forces, outside the grasp of even gods. Others say that avatars are reborn when they die and are as old as worlds. Generally there is almost nothing known about them and their potential.

Friend of the Elements

When you choose this monastic tradition at level 3, you learn how to speak and understand Primordial, the language of Elementals.

Manipulate Elements

You know the cantrips shape water, produce flame, mold earth and gust. You only need to use somatic components to cast them. For you, manipulating elements is the same using a them as an extension of your body. Your abilities are therefore not magical in nature, that is why these four cantrips can't be cancelled by magic like counter spell.

Wield Element

On your turn you can choose one of the elements to wield by spending a Ki point. For the duration of minutes equal to your wisdom modifier you gain the benefits of wielding that element (see below). To wield any element you need to uphold concentration, same as concentration spells. You can choose to end Wield Element at any time. At 3rd Level you can only wield one element at the time.

Wield Water. While wielding water all your unarmed strikes have reach (10ft) and do slashing instead of bludgeoning damage. The attack and damage modifiers are wisdom instead of dexterity or strength. To activate Wield Water there needs to be at least one cubic foot of water in the vicinity of 15 feet. Succeeding a stunning strike with the benefits of Wield Water on a creature that has an amount of a 5-foot cube of water within 5 feet of it's vicinity will freeze the creature and it will take an additional Martial Arts Die of cold damage from the attack.

Wield Earth. Your unarmed strikes can attack creatures with range 15 feet and with disadvantage up to 60 feet. The attack and damage modifiers are wisdom instead of dexterity or strength. To do this the ground below you and the creature you attack has to be earth or rock and has to be connected. Alternatively you can also use walls or ceilings that you are able to touch/ touches the creatures space. The attacks you make with this will look like pieces of earth and rock that you bend out of walls, ceilings and floors from a distance to hit your foe, because of this, unarmed strikes while wielding earth still count as melee attacks. Because attacks you make with the benefits of Wield Earth elaborate somatic movements, you loose 10 feet of your movement for each attack you make with it. Succeeding on a stunning strike with the benefits of Wield Earth on a creature that has at least an amount of a 5-foot cube of earth or rock within 5 feet of it's vicinity will restrain the creature until it succeeds a strength saving throw, which it can roll on each of it's turns.

Wield Fire. Your unarmed strikes do fire damage instead of bludgeoning damage. The attack and damage modifiers are wisdom instead of dexterity or strength. Replacing one of your unarmed attacks, you can also make a ranged attack. Ranged attack rolls are the same as melee but you can't add your damage modifier to damage rolls of ranged attacks. The normal range is 30 feet and the long range is 120 feet (attack with disadvantage). You can't use wield Fire underwater. For the duration of Wield Fire the flame in your hand will be a light source as bright as a torch.

Wield Air. You can replace one of your unarmed strikes to do an Air push. Air push counts as attack action, which means it allows the benefits from Martial arts and Extra attack. With Air Push you can push, in any one direction of your choosing, creatures within 5 feet of you that have the size medium or smaller. You can push large creatures but only half the distance as if it were a medium one. The creature can try to withstand the effect with a strength or dexterity save when it's standing on the ground. An airborne creature can only try to evade it with a dexterity save with disadvantage. You can also push yourself as long as as you have the benefits of unarmored movement. Air push can only be used if yours and the creature's space are filled with air. Air push disperses gas or vapor, and it extinguishes candles, torches, and similar unprotected flames in the space a creature gets pushed through.
From level 3 forward you can push one creature up to 20 feet in any direction on the ground or 10 feet up
From level 5 forward you can push one creature up to 30 feet in any direction on the ground or 20 feet up.
From level 11 forward you can push one or two creatures up to 40 feet in any direction on the ground or 20 feet up.
From level 17 forward you can push one or two creatures up to 50 feet in any direction on the ground or 30 feet up.

At 6th Level you can swap between elements once per turn without spending a Ki point. When you swap elements, the time for how long you can uphold Wield Element does not reset.

At Level 11 You can wield two elements at a time, but have to spend another Ki point for to activate the second element. The duration of Wield Element will not reset when you activate the second element.  Breaking concentration will end all elements you are wielding. You can't accumulate the benefits of both elements in one attack, but can use different ones in separate attacks. For example, when you have Wield Fire and Wield Water active, you can attack once with Water (reach and slashing damage) and with your extra Attack once with Fire (fire damage).

Duality of Water and Fire

At level 6, training with the elements has accustomed your body to ice and fire. You now have resistance to cold and fire damage. Water can no longer impair your movement, which means your swim speed is the same as your walking speed.

Duality of Earth and Air

Starting at level 11 you can spend a Ki point to do one of the following:

Air Slam. You do this as a bonus action. All creatures (you included) in a cylinder of 15 feet radius around you and 60 feet above and below you have to make a strength save or be knocked prone. Airborne creatures automatically fail, slam to the solid ground (if available) and take 1d8 bludgeoning damage per 5 feet they were above ground beforehand and are also knocked prone. If you were to take damage yourself by using Air Slam you can reduce the damage you'd take by using Slow Fall as a reaction. Air Slam disperses gas or vapor, and it extinguishes candles, torches, and similar unprotected flames in the space it can affect creatures. Air Slam can only be used in space filled with air and can't travel through walls, roofs or floors.

Earth Armor. As an action, you get an AC of 20 and 5 temporary hit points until the temporary hit points are gone or 30 seconds are over. You can also choose to disperse the armor at any time. For that duration it is as if you were wearing a plate armor, which means that you loose benefits from Unarmored Movement and other disadvantages as stated in the rules if you don't have heavy armor proficiency. To activate Earth Armor there have to be at least ten cubic feet (~2.2 x 2.2 x 2.2) of earth or rock in the range of touch which will be used to create the armor. Attacks with the benefits of Wield Earth will only use 5 feet of your movement while Earth Armor is active.

Avatar State

At level 17 you can spend four Ki points to activate Avatar State and gain the benefits of all four elements of the feature Wield Element for it's duration. You can't accumulate the benefits of multiple elements in one attack, but can use different ones in separate attacks. Additionally, you can cast one of the cantrips you gained with the feature Manipulate Elements once on your turn without spending an action. Avatar State will last for minutes equal to your Wisdom Modifier. While active you are able to fly at the same speed as your walking speed as long as you have the benefits of unarmored movement. You do not need to uphold concentration for Avatar State, it only ends when the time runs out or you drop to 0 hit points. At the beginning of Avatar State you gain temporary hit points equal to your Wisdom score, which will disappear when Avatar State ends. While Avatar State is active, you ignore all effects of exhaustion from level 1 to 5.

If you drop to 0 hit points while Avatar State is active, you die immediately without rolling death saves. When Avatar State ends you gain one level of exhaustion.