I am just curious about the potential interaction between Cleave and great weapon mastery. Cleave is not clear if it is considered a part of the same action as the attack that triggered it.

If Cleave is considered as part of the same action then this potential means that it can trigger the great weapon mastery block of the Great Weapon Master feat when used off of an attack made as part of an attack action.

Personally I believe this is the case but thought to seek insight/clarification from others on if this is correct.

In my opinion, the Cleave attack is NOT an Attack action attack:

Cleave

If you hit a creature with a melee attack roll using this weapon, you can make a melee attack roll with the weapon against a second creature

This is a feature that is allowing a creature to make an attack and this feature does not explicitly say anything about the attack being part of an Attack action like the Nick property does, for example.

The fact that not all attacks are part of an Attack action and that there is a distinction in general between various sources of attacks can be seen from this rule:

Making an Attack

When you take the Attack action, you make an attack. Some other actions, Bonus Actions, and Reactions also let you make an attack.

Quote from up2ng>>

In my opinion, the Cleave attack is NOT an Attack action attack:

Great Weapon Master does not require it to be an attack action attack, it requires that you hit as apart of the attack action.

So what matters here is if is to be part of the same action that caused it, it also does not say it is a free action either.

Since cleave can also be triggered as part of a bonus action, reaction, or another type of action that involves a melee weapon attack (I.e. true strike), it is not going to say it's part of the attack action since there may not even be an attack action. So the question is what action is it considered to be a part of.

As I understand the rules, Cleave could potentially be used as part of an Attack Action, Bonus Action or reaction.

If you take the Attack Action, in my opinion, Cleave becomes part of that action.

I've changed my mind. I agree with this answer from Plaguescarred.

Yea this seems like an oversight tbh, it should have had something like "as part of the same action" in there somewhere. As it stands it seems to be an attack roll being made outside of actions/bonus actions/reactions and that leaves it in a strange place.

Nothing in Cleave say the extra attack is part of the Attack action like Nick does, presumably so it can be used on an attack made as a Bonus Action or Reaction such as an Opportunity Attack.

Quote from Thezzaruz >>

Yea this seems like an oversight tbh, it should have had something like "as part of the same action" in there somewhere. As it stands it seems to be an attack roll being made outside of actions/bonus actions/reactions and that leaves it in a strange place.

 Agreed, IMO it is meant to be part of the same action and not allow things like moving in between the attacks, similar to how the "Cleave through creatures" optional rule currently works where the damage to a second creature is part of the same original attack. It is simply lacking the appropriate language because it's essentially adapted from the Ranger's Horde Breaker subclass feature.

Maybe this is useful for the thread. From the article "Your Guide to Weapon Mastery in the 2024 Player's Handbook": 

Cleave

Example Weapon: Greataxe

If you’ll be wading into the thick of battle, you’ll want to consider grabbing a weapon with the Cleave property.

These heavy weapons can slash through opponents. If you hit a creature with a melee weapon attack, you can make a second attack against a creature within 5 feet that is also within your reach. When you hit with the second attack, you can roll your weapon’s damage, but you don’t add your ability modifier unless it’s negative.

This is excellent in combination with the Halberd, which has Reach and Cleave, allowing you to Cleave into enemies in an extended range.

Quote from Thezzaruz >>

Yea this seems like an oversight tbh, it should have had something like "as part of the same action" in there somewhere. As it stands it seems to be an attack roll being made outside of actions/bonus actions/reactions and that leaves it in a strange place.

It's only strange in that it's rare, but it's most likely  deliberate. Giving characters additional attacks can quickly spiral out of control, they don't want this having unforeseen interactions with features that let you do X whenever you make an attack as part of the Attack action. Two-handed weapons already scale the best with Extra Attack, Haste, Opportunity Attacks and per-weapon buffs (e.g. Elemental Weapon.) Having the equivalent of Nick on a two-handed weapon is quite powerful.

Quote from InquisitiveCoder >>

It's only strange in that it's rare, but it's most likely  deliberate. Giving characters additional attacks can quickly spiral out of control, they don't want this having unforeseen interactions with features that let you do X whenever you make an attack as part of the Attack action. Two-handed weapons already scale the best with Extra Attack, Haste, Opportunity Attacks and per-weapon buffs (e.g. Elemental Weapon.) Having the equivalent of Nick on a two-handed weapon is quite powerful.

I foresee there being a lot more confusion and unintended issues arising form an attack (well from anything you can do really) that takes place outside the normal rules and action economy that there would be if the rule was written so that it worked within the existing framework.

Just from the stuff you mentioned I found a question about Haste. It limits which actions you can take with the additional action it gives you and if you choose the Attack Action then it limits you to only one attack. But if the additional attack from Cleave is its own freestanding-not-part-of-the-action-that-enabled-it kind of attack then it wouldn't be prohibited by Haste's limitation right?

As written, Haste shouldn't limit Cleave's extra attack, but would limit Nick's  extra attack of the Light property.

Funily, without the Mastery and just Light property or Dual Wielder feat, it would not limit the extra attack as a Bonus Action. 

Quote from Thezzaruz >>

Just from the stuff you mentioned I found a question about Haste. It limits which actions you can take with the additional action it gives you and if you choose the Attack Action then it limits you to only one attack. But if the additional attack from Cleave is its own freestanding-not-part-of-the-action-that-enabled-it kind of attack then it wouldn't be prohibited by Haste's limitation right?

 I don't see any issues with that:

• Cleave is limited to once per turn so adding Haste (or Action Surge) into the mix doesn't let them get more Cleave attacks.
• If the player uses their main action to Attack, they're going to get their Extra Attacks + Haste attack + Cleave anyways.
• Haste still triggers the TWF bonus attack under both the 2014 and 2024 rules, as long as you don't try to use the Nick property as well.
• It's not even against the spirit of the rules since Cleave is supposed to be one weapon attack that follows through to hit a second creature.

Seems to me that cleave is a part of what ever action you used to get it. Cleave seems to be able to be used with the attack action, magic action, bonus action, and reaction so long as its still limited to one use on the current turn. Maybe there are some martial creature blocks developed that have weapon masteries on them too for multiattack?

Thanks for the feedback

If you take the attack action and use cleave on that attack action, labeling the cleave as NOT an attack on the attack action makes no sense since it requires an attack roll.  Anything that requires an attack roll is an attack. 

So i think the way i am going to run it is:

Cleave attack that is triggered by an attack on the attack action does add great weapon master bonus.  GWM feat does not require an "Attack on the attack action", it only requires you hit a creature "as a part of the attack action".  Cleave seems to fit this.

Cleave attack, that is triggered by an attack from a bonus action or reaction does not add great weapon master bonus.

Any cleave attack does add magical bonuses to damage.

Spells like hunters mark or divine favor are added to the cleave attack.

Extra weapon damage dice (like extra 1d6 from frost brand) do apply to cleave attack.

It seems like there are quite a few ways to boost the damage of the cleave attack.  Enough to make it really good in the right circumstances.

@Masterofki maybe you wanted to reply in your new thread instead of this one?

EDIT: fix link.

Quote from TarodNet >>

@Masterofki maybe you wanted to reply in your new thread instead of this one?

Thank you!

So my level 5 barbarian has GWM and has been using a halberd and cleave when enemies are adjacent and within 5' of each other. I just got my extra attack.

1. Attack (hit) one enemy + cleave the one next to it
2. Extra Attack (hit) one enemy + cleave the one next to it. It dies.
3. Bonus action attack from GWM (hit) + cleave the one next to it.

Now let's add a potion of speed into the mix.

1. Attack (hit) one enemy + cleave the one next to it
2. Extra Attack (hit) one enemy + cleave the one next to it. It dies.
3. Bonus action attack from GWM (hit) + cleave the one next to it.
4. Haste attack (hit) + cleave the one next to it

8 attacks at Level 5?

Quote from Oatymon >>

So my level 5 barbarian has GWM and has been using a halberd and cleave when enemies are adjacent and within 5' of each other. I just got my extra attack.

1. Attack (hit) one enemy + cleave the one next to it
2. Extra Attack (hit) one enemy + cleave the one next to it. It dies.

Incorrect. Cleave specifies that it can only be used once per turn

Cleave

If you hit a creature with a melee attack roll using this weapon, you can make a melee attack roll with the weapon against a second creature within 5 feet of the first that is also within your reach. On a hit, the second creature takes the weapon’s damage, but don’t add your ability modifier to that damage unless that modifier is negative. You can make this extra attack only once per turn.