Can any Attack action by a monk trigger Flurry of Blows?

Question

Reading over the Monk I saw that for Martial Arts:

When you use the Attack action with an unarmed strike or a monk weapon on your turn, you can make one unarmed strike as a bonus action.

This implies that non-monk weapons do not count towards being able to make this single unarmed strike. However, when looking over Flurry of Blows:

Immediately after you take the Attack action on your turn, you can spend 1 ki point to make two unarmed strikes as a bonus action.

The requirement doesn't seem to be there anymore, and I didn't see where this discrepancy was covered in this answer to a similar question about the limitations of an unarmed strike. This answer to a duplicate question says that you can use flurry of blows as a bonus action on any form of attack.

So does the limitation really only exist on a single unarmed strike, but you can use whatever attack action you want to trigger Flurry of Blows?

Answer 1

Yes, it can

Why the cognitive dissonance? Martial Arts is one Monk class feature, Flurry of Blows is a completely different Monk class feature and each has its own independent criteria for allowing their respective bonus actions.

However, if the attack you use to allow the Flurry of Blows is neither unarmed or a monk weapon and you are still holding it when you make your unarmed attack, their damage is 1 + STR bonus rather than monk die + STR/DEX bonus as you do not qualify for the monks unarmed benefits. For your proposed Druid/Monk build this is a real problem as most beasts are always wielding non-monk weapons like claws or bites.

Answer 2

You don't want to do this. The answer strictly as the question is asked is yes, but it's with significant penalty and therefore my answer is a resounding NO!

You could in theory, but you will only do normal unarmed strike damage of 1 + Strength modifier.

Per PHB pg. 78, under the heading of Martial Arts:

You gain the following benefits while you are unarmed or using monk weapons and your aren't wearing armor or wielding a shield:

• You can roll a d4 in place of the normal damage of your unarmed strike or monk weapon. This die changes as you gain monk levels...

Additionally, in the same section but a different bullet point:

When you use the Attack action with an unarmed strike or a monk weapon, you can make one unarmed strike as a bonus action.

You therefore need to remain unarmed or be wielding only approved monk weapons to get the benefit of a monk's unarmed strike bonus when using your extra unarmed strike from Martial Arts or Flurry of Blows. Otherwise, you only do 1+Str damage per success attack roll.

Furthermore, if you aren't unarmed or or wielding monk weapons, you will be unable to make any extra attack as your bonus action. So you are losing in two ways.

Assuming 5th level, the greatest number of "effective" attacks will be a max of 2, where as a monk armed with a monk weapon or unarmed will be able to attack "effectively" 3 times without using a ki point, and 4 times if using a ki point.