Base Class: Monk
The Way of the Mystic Avatar features some of the most devoted monks. These monks seek to lock themselves away from the world, denying the limits of the physical world and replacing it with a reality that they create for themselves. Known as wu jens, these monks cast their minds into the world, seize control of its fundamental principles, and rebuild it.
In practical terms, wu jens excel at controlling the forces of the natural world. They can hurl objects with their minds, control the four elements, and alter reality to fit their desires.
Elemental Disciplines
Starting when you choose this tradition at 3rd level, you learn an elemental discipline of water, earth, fire, or air. You learn additional disciplines at 6th, 11th, and 17th level.
Blood Bend
You learn the shape water cantrip, with wisdom as your spellcasting ability. As an action, you can spend 1 to 7 ki points and choose one creature you can see within 60 feet of you. The target must make a Constitution saving throw against your ki save DC. On a failed save, a target takes 1d10 necrotic damage per ki point spent on this ability and you can control the creature’s action, bonus action, and movement on its next turn (but cannot cause the creature to cast a spell). On a passed save, a target takes half as much damage and is not controlled.
Combustion
You learn the control flames cantrip with wisdom as your spellcasting ability. As an action, you spend 1 to 7 ki points and choose one creature or object you can see within 120 feet of you. The target must make a Constitution save against your ki save DC. On a failed save, the target takes 1d10 fire damage per ki point spent, and it catches on fire, taking 1d6 fire damage at the end of each of its turns until it or a creature adjacent to it extinguishes the flames with an action. On a successful save, the target takes half as much damage and doesn’t catch on fire.
Conjure Quicksand
You learn the mold earth cantrip, with wisdom as your spellcasting ability. As an action, you can spend 1 to 7 ki points to seize control of a dirt, stone or wooden surface you can see within 30 feet of you. A 5 foot square of this surface becomes difficult terrain for one minute. Whenever a creature starts its turn in this area, or enters this area for the first time on its turn, it must succeed on a Dexterity saving throw against your ki save DC or take 1d10 force damage per each ki point spent on this ability and be restrained until the start of its next turn. On a successful save, a creature takes half damage and is not restrained.
Wind Stream
You learn the gust cantrip with wisdom as your spellcasting ability. As an action, you spend 1 to 7 ki points to create a line of focused air that is 30 feet long and 5 feet wide. Each creature in that area must make a Strength saving throw against your ki save DC, taking 1d8 bludgeoning damage per ki point spent and being knocked prone on a failed save, or half as much damage and not being knocked prone on a successful one.
Telekinetic Grasp
At 6th level, you gain the ability to move objects with your mind. Choose one object you can see within 60 feet of you that isn’t being worn or carried by another creature and that isn’t secured in place. It can’t be larger than 20 feet on a side, and cannot weigh more than 250 pounds.
As an action, you move the object up to 60 feet, and you must keep the object within sight during this movement. If the object ends this movement in the air, it falls. If the object would fall on a creature, the creature must succeed on a Dexterity saving throw against your ki save DC or take 1d6 bludgeoning damage for every 10 feet the object falls.
You can use this ability a number of times equal to your intelligence modifier plus your wisdom modifier (minimum of 2). You regain your expended uses at the end of a long rest.
Restorative Reality
Beginning at 11th level, you can project an aura of resilience. While you aren’t incapacitated, you can use a bonus action to spend 1 or more ki points to heal one or more creatures within 30 feet of you who can see you. You can include yourself as one of the creatures healed by this bonus action. Each creature regains 1 hit point for each ki point you spend.
Quickened Reality
Starting at 17th level, you project an aura of speed. While you aren’t incapacitated, any creature of your choice other than yourself within 30 feet of you who can see you can take the Dash action as a bonus action and has a +2 bonus to initiative rolls.
Since the Mystic was broken, this is pretty good. It´s like what the 4 Elements Monk should´ve been. Maybe add a few more Disciplines, like something to do with ice, interacting with elemental creatures/monstrosities which adapted to different environments, electricity currents, smokescreens through fire manipulation, or plant movement.