Can you use Stunning Fist on an Attack of Opportunity?

[BlueWitch]

This actually led to a big fight at our table. (Mostly due to some idiotic player on player in-fighting. Lawful vs. Chaotic. Go figure....>__<')

The main argument was is activating a Stunning Fist a Free Action (that has to be used fully on your turn) or a Non-Action part of another one.

As DM I ruled the Monk could. But looking back I can't really find anything for it. My Halfling Rogue player was pretty angry.

(to further add complexity, the "Monk" was using a Ki Focus Kusarigama, and had Lunge.)

[GoodbyeSoberDay]

Deciding to use the Stunning Fist feat as part of your attack is indeed a non-action - you simply have to declare you're using it before the roll. If it was a free action it would be specified as such in the feat description. Sorry about the heated PVP.

[MaxiDuRaritry]

This actually led to a big fight at our table. (Mostly due to some idiotic player on player in-fighting. Lawful vs. Chaotic. Go figure....>__<')

The main argument was is activating a Stunning Fist a Free Action (that has to be used fully on your turn) or a Non-Action part of another one.

As DM I ruled the Monk could. But looking back I can't really find anything for it. My Halfling Rogue player was pretty angry.

(to further add complexity, the "Monk" was using a Ki Focus Kusarigama, and had Lunge.)There's no action listed, and it mentions simply declaring it on an unarmed attack roll 1/round. I'm pretty sure it can be done any time you make an attack, which includes AoOs.

So unless someone can find specific text saying otherwise...

[Psyren]

Yes, it is usable with any unarmed attack (including AoOs, iteratives, Snap Kick etc.)

[mabriss lethe]

The caveat here is that you can only pop it off once per round, so if you've already used an attempt on your turn you can't pop off another until your next turn. If you didn't use it, then it's still available for use on an AoO.

[Biggus]

I can't see any reason you can't, or anything that says it's a free action.

[SirNibbles]

An attack of opportunity is a single melee attack you can make when you’re active in combat and an opportunity presents itself. Making an attack of opportunity isn’t considered an action...

Rules Compendium, page 18





Not an Action: Some activities are so minor that they are not even considered free actions. They literally don’t take any time at all to do and are considered an inherent part of doing something else. For instance, using the Use Magic Device skill (page 85) while trying to activate a device is not an action, it is part of the standard action to activate a magic item.


Player's Handbook, page 139





Use Feat
Certain feats... let you take special actions in combat. Other feats do not require actions themselves, but they give you a bonus when attempting something you can already do... Some feats... are not meant to be used within the framework of combat. The individual feat descriptions... tell you what you need to know about them.


Player's Handbook, page 145





Benefit: You must declare that you are using this feat before you make your attack roll (thus, a failed attack roll ruins the attempt). Stunning Fist forces a foe damaged by your unarmed attack to make a Fortitude saving throw (DC 10 + 1/2 your character level + your Wis modifier), in addition to dealing damage normally. A defender who fails this saving throw is stunned for 1 round (until just before your next action).

Player's Handbook, page 101


No action is mentioned so none should be required.

However, there is an issue of the Stun only lasting until just before your next action. Is that an oversight on the part of the devs who may have failed to consider that an AoO stunning fist would not end just before your next action or does it show that it was intended to only be used on your own turn?

Add this to the list of rules that needs to be clarified by a few simple words.

[Psyren]

To be fair, even if you go with the short duration interpretation (stun them before your next turn, and then they're free again right before that turn starts) that's still beneficial - it means you've disarmed them (stunned characters drop anything held), disrupted any spells they were in the process of casting, stopped their movement etc.

[BlueWitch]

To be fair, even if you go with the short duration interpretation (stun them before your next turn, and then they're free again right before that turn starts) that's still beneficial - it means you've disarmed them (stunned characters drop anything held), disrupted any spells they were in the process of casting, stopped their movement etc.

Aye carumba! We actually forgot about that! lol

at the time the Halfling Rogue just lost his turn and took the AC penalty. (He failed the Fort save) but regardless he didn't survive the Flurry of Blows afterward.