Very cool and well-written. My only worry with this set of features is that it might leave you very starved for reactions in many battles. Maybe you could swap one of the benefits of Abandonment for an extra reaction each round?

Very interesting idea!

I haven't thought of it yet, but now that you mentioned it, it seems very cool and appropriate for a higher-level feature I think.

Not to mention it would also help justify a bit more the 10 ki points cost.

Maybe while you are using the Abandonment, if you then take the Dodge action or use the Patient Defense feature, you get this additional reaction until the start of your next turn.

This is relatively minor, but for the bonus proficiencies I think it would be better to either give more proficiency choices and have the player choose 2 of them (perhaps nature, Survival, or Athletics?), or to include language that, if the player already has one of those proficiencies, they can select a different one instead. Mostly because Monks already have the option of Acrobatics proficiency, or they might have Perception thanks to their race or background. Some alternatives help avoid it potentially becoming a redundant feature.

Part of me is concerned that the Flurry of Streaming Blows is a little too good, but Monks generally aren't overpowered in terms of damage output. I think there's some potential to abuse the feature in a multiclass build of some kind... 6 attacks in a round is an awful lot if you can tack on something like Hunter's Mark, but it is an 11th level ability, so it's not like you can just take a quick Monk dip to unlock the feature. I've been told I have a tendency to lean "too weak" in my homebrew stuff, so maybe that's just my paranoia, but although I think there's potential for abusing the feature, I don't think there's any real, obvious problem with it.

About the bonus proficiencies that you mentioned, I was thinking on adding the following: "When you choose this monastic tradition at 3rd level, you gain proficiency in the Acrobatics and Perception skills. If you already have proficiency in these skills, you gain expertise in them instead."

And concerning the Flurry of Streaming Blows combined with Hunter's Mark, this spell only adds damage for weapon attacks. Flurry of Streaming Blows gives you unarmed strikes.

But thanks for the heads up about Flurry of Streaming Blows, I'll try to think of something, although I don't think it's too powerful. Compared to many classes, Monks are usually not that great, so I was trying to buff them a bit.

That's a good point about Hunter's Mark... I'm so used to it just tacking onto anything the Ranger in my game does I didn't realize it was limited to weapon attacks. I think that Monk's Flurry of Blows exclusively being Unarmed Strikes does help reduce potential for abuse... you can't sneak attack with them, or smite with them. I'm sure someone who takes the time to compare all the different class features and spell combinations could find a way to abuse the feature, but considering monks pretty consistently underperform in damage output there's room to be pretty generous with them.

I know, for example, that I'm playing a campaign where one of the players is using the UA version of Astral Self monk, which gets more attacks per round than the official version, and can even boost one hit with an additional Martial Arts Die worth of damage, and she still outputs less damage per round than my Storm Herald Barbarian. Although the opportunity to stun is still pretty useful and has some potential for abuse, but a monk by default already gets 4 opportunities to stun enemies (assuming they have the ki to fuel it), so getting two more at the cost of 3 ki seems like a fair tradeoff.

An unarmed strike is still a “melee weapon attack” and can in fact benefit from hunter’s mark.

Edit: That’s one of the reasons a 2-level dip into Ranger is such a good multiclass for almost every Monk. That and the weapon proficiencies for Dedicated Weapon, among other things like the Fighting Style for stuff like Blind Fighting. The best thing any Monk can do to overcome the challenges of being a Monk is 2 levels of Ranger IMO.

Sorry for the misinformation then, I had completely forgotten that unarmed strikes also count as melee weapon attacks.

Quote from turtrooper >>

Very interesting idea!

I haven't thought of it yet, but now that you mentioned it, it seems very cool and appropriate for a higher-level feature I think.

Not to mention it would also help justify a bit more the 10 ki points cost.

Maybe while you are using the Abandonment, if you then take the Dodge action or use the Patient Defense feature, you get this additional reaction until the start of your next turn.

 The feature already gives you the benefits of Dodge though. Maybe instead of those benefits being automatic, you can use Patient Defense for free for the duration?