This document features a complete rework of the Dungeons and Dragons 5e Monk class, with 4 unique new subclasses. 

The purpose of this rework was to create a new expression of the fantasy Monk archetype, focused more on utility spellcasting through the aesthetic lens of mysticism.

A notable feature of this rethinking of the Monk is their unique interactions with spellcasting through Prowess, allowing the Monk to weave spellcasting into normal attacks, and rewarding them for concentrating on spells. 

This document also features 4 new subclasses:

Way of the Blood. A selfless monk, capable of empowering healing by sacrificing their own life force, allowing allies to drain life from their opponents, and regenerating themselves.

Way of the Stone. A battlefield control caster, able to shape their surroundings and encapsulate their enemies in stone.

Way of the Tempest. A high damage attacker, who uses lightning to increase the reach of both their attacks and spells, allowing both to bounce between targets.

Way of the Mind. A selfish psionic fighter, bolstering their own defenses while assaulting the minds of others.

If you are interested in the thoughts that went into the design, keep reading! Otherwise, the document can be found by scrolling down furiously. Leave a comment if you intend to try this out in your own game!

This document was created using Homebrewery!

Design Thoughts

What follows is a detailed walk through the thoughts that lead to the creation of the document, including a closer look at some of the features of the new Monk. I include this because I believe understanding the intention of the design helps to fully understand it; it is not at all required reading — in fact, I do not recommend reading this before downloading and reading the new Monk class document. So keep scrolling and come back later!

Background

I think it is important to understand that I don't think anything is wrong with the official version of the Monk. The class doesn't appeal to me as a player, but not every class needs to, nor even should. The inspiration for this rework instead came from ideas I had about new ways of interacting with Concentration, an important aspect of spellcasting in Dungeons and Dragons.

Concentration

Concentration is a mechanic that defines the limits of spellcasting. Certain spells with a duration require the caster to maintain concentration to maintain the effect. Taking damage, or suffering a similarly disruptive event, forces the caster to make a Constitution saving throw to maintain concentration, with the DC set at 10 or half the damage suffered, whichever is highest.
  At the same time, concentration limits how many spells a caster can have active, as they can only concentrate on one spell at a time.

The effect of this is simple, although it may at first be confusing to newcomers: Casters cast one cool spell, then try to keep it going for as long as possible, casting non-concentration spells meanwhile. When fighting casters, characters can end negative effects by breaking concentration through attacks. 
  All round an interactive mechanic that encourages specific play. It also acts as a balancer, allowing certain spells to be a little bit more powerful, as casters can only use one of them at a time. Any spell with a duration which does not require concentration, such as Blindness/Deafness or Spiritual Weapon, are made more powerful simply by the fact that they can coexist with concentration spells.

But beyond a few class features and the feats War Caster and Mage Slayer, very few systems interact with concentration. This is not a bad thing! It keeps the game simple for newer players. But with this Monk class, I wanted a class that cared more about concentration than most.

Prowess, Split Focus, and Rebound

Prowess replaces the original Monk's Ki feature. It offers condensed and altered versions of Flurry of Blows, Step of the Wind, and Patient Defense, that are designed to work better with action economy taxing spellcasting and maintaining concentration. But more importantly, it provides the classes first and most important interaction with concentration spells: A +1 bonus to attacks and damage rolls per level of spell being concentrated on. With a half-caster's spell progression, this allows for +1 at level 2, +2 at level 5, +3 at level 9, +4 at level 13, and +5 at level 17.
  This is a huge buff to the Monk's damage output and consistency of attacks without the need for magical items, but it comes at the risk of completely disappearing if the character drops concentration, which is a common occurrence for a melee spellcaster.

Split Focus builds on the idea of Monks concentrating on spells for increased effectiveness by allowing them to briefly concentrate on more than one spell. This comes at the cost of making both spells more vulnerable to disruption of concentration, but also increases the effect of Prowess (although additional spells only affect damage). 

Finally, Rebound allows the Monk to recast spells when they lose concentration, allowing them to maintain their Prowess bonus. As a level 20 feature, the balance of this ability is less important, but it's still worth thinking about.

These features have an incredible impact on the power of the Monk, especially at the higher levels. While a +1 weapon early in the game will not break anything, a +4 bonus at level 13 goes beyond items the players could find, and potentially stacks with similar effects on magic items. This also conflicts with Bounded Accuracy, a 5e design philosophy concerned with homogenizing bonuses to rolls and DCs and ACs, with the goal of less disparity between high and low level of play, and to allow low level challenges to still affect higher level characters. With the huge bonus to attacks and damage that this set of features can provide, the Monk may well pull far ahead of other classes, hitting more attacks and thus dealing more damage than anyone in their party. This could be a huge problem! And it is only truly offset by the ethereal nature of concentration, and the slight nerf to the number of attacks this Monk can output in a round.

This iteration of the monk has not been tested yet, although I hope to do so in the near future. The solution I imagine to the balance issue is to limit the bonus per level of spell to half rounded up. That would result in a +1 at 2, +1 at 5, +2 at 9, +2 at 13, and +3 at 17, which is much close to magical weapons (and the Magic Weapon spell). But I am keeping it as-is for now!