Meditation, Mediation, Devastation: A Monk's Guide
How does one Monk? A Monk is a fast, hit and run style character. They get in, they trash the place, they get out. They are, without exception, the fastest class, and the only thing that could improve that is dipping two levels into Rogue for Cunning Action.
Stats:Strength: Thanks to your Martial Arts, you can completely ignore Strength in most cases. If, however, you want to make a Grappling Monk, this will be your main stat.
Dexterity: AC, Intitaitive, Attacking and Damage, all of it can be done with Dexterity for you. Even if this isn't you're main stat, you're going to want it quite high for the first two reasons.
Constitution: You don't want to get hit. Both your playstyle and your Hit Dice suggest you really don't want to get hit. But more likely than not, you will get hit at some point. And have HP when you do is good.
Intelligence: Monks are wise, not book smart. But really, intelligence does nothing for you.
Wisdom: Your ability to spot the hidden, the saving throws you inflict, and a large portion of your AC will all come from your Wisdom. That said, it's not as essential as Dexterity, so if you're stuck between which to boost, Dex first.
Charisma: All that time meditating hasn't really helped your social skills much.
Class Features:Unarmored Defense: Your stuck with it and it scales slowly. Good news is the only class that can out-AC you by level 20 is the Barbarian. Well, assuming you maxed Wisdom and Dexterity. Unfortunately it doesn't work with a shield, unlike the Barbarian's.
Martial Arts: Now you're talking. This is, without a doubt, the easiest way to get a bonus action attack with full modifiers, ever. Also all your Monk weapons (including your Unarmed Strikes) can run off of Dexterity.
Two very important things to note here: Both the damage die and the using of Dexterity are optional. You'll want your Unarmed Strikes to use the Monk's damage die for sure, but stick with a weapon until 5th level at the earliest (11th if you're using a Versatile weapon two-handed).
Ki: Ki, all your really good stuff revolves around Ki. You have to pace yourself, as it only regenerates when you rest (short or long), but when you do use it, it can be brutal. You also get your Ki Save DC defined here, it's exactly what you'd expect it to be.
- Flurry of Blows: In most cases, if you're going to spend Ki, it's going to be here. Especially if you're an Open Hand Monk.
- Patient Defense: It can be useful, namely because it lasts longer than Disengaging.
- Step of the Wind: Outclassed If you pick up Cunning Action, but otherwise being able to not provoke when you retreat is good.
Unarmored Movement: You're a squishy striker, having enough speed to get in, do your job and get out is essential. Being able to water walk and go Matrix style is also cool.
Deflect Missiles: Reducing the ways you can effectively be attacked is good. Being able to redirect attacks is just icing on the cake.
Slow Fall: Or as I call it "Why Not Jump". The amount of times you'll be falling will vary quite massively, but it's handy to have when you do.
Extra Attack: More attacks is good. Plain and simple.
Stunning Strike: But when combined with this, well. Stun on your first strike and your second (and possibly your Flurry) has advantage. It can't attack you, can't move and can't make Strength or Dexterity saving throws.
Ki-Empowered Strikes: Not that you have a choice about it, but this is needed for keeping up late-game.
Evasion: This lets you make a
Stillness of Mind: Yet more ways to stop you being locked down. Charmed and Frightened are bad when you want to take someone out, spending an action to avoid that, while painful, is your best course of action while under either.
Purity of Body: Flat out immunity to Poison and Disease is nothing to sneeze at.
Tongue of the Sun and Moon: It's use depends entirely on how much your DM uses other languages. That and in general most things speak Common.
Diamond Soul: Look closer. Do you see it? All saving throws. So that includes Death Saving Throws. Not that great since you want to avoid being in that situation in the first place, but helpful when you've no choice.
Timeless Body: Unless your campaigns last for a century or more, this is basically useless.
Empty Body: Ignoring the second part, unless your opponents have True Sight you are going to want this in every combat. Even if they have True Sight you might still want it for the damage resistance. And it's all concentrationless. Even better (somehow) if you've Cunning Action (Rogue 2), as you can sit next to the enemy completely hidden and Stun them if they move away.
Perfect Self: Varies by how much you spend your Ki points. If you manage to burn through all 20 before a short rest, this can tide you over. Just be sure to spend them all, as you don't get any if you've 1-3 Ki Points remaining.