How to rewrite a Homebrew feat that interacts with Two-Weapon Fighting?

Question

In my current campaign, I have added a new feat that intentionally makes Two-Weapon Fighting much stronger:

Dual Flurry

Prerequisite: Extra Attack, or an equivalent feature

Once per turn, when you perform Two-Weapon Fighting, you may make two additional attacks with the other weapon instead of one.

Now, I want to make clear: this is not a question about whether this feat is balanced. My group has already performed playtesting with this feat (alongside some other adjustments to how two-weapon fighting works) and have found the power level to be acceptable. With a caveat.

The issue I've run into is that due to ambiguity in the wording of the feat, it opens up the exploitable ability to make too many attacks with the same weapon in a single turn—something I didn't intend for when adding the feat for use in the campaign. This obviously isn't problematic in most situations: many characters use two of the same weapon when two-weapon fighting, so which weapon they use isn't meaningful. But there are many situations where characters might have a much stronger weapon in one hand than in their other; like, for example, an Eldritch Knight that has a summoned Shadow Blade in one of their hands.

My thought process was that the feat would permit a character [at level 5, the lowest level the feat can be legally obtained] to make four total attacks: two with one weapon, and two with the other. But per the wording of the feat, said character can instead make three attacks with one weapon, and one attack with the other, by using ordering like this:

1. Character is holding a Shadow Blade in one hand, and a Shortsword in the other.
2. Character takes the Attack Action, and makes an attack with Shadow Blade
3. Due to the Extra Attack feature, they can make another attack; they use the Shortsword
4. Two-Weapon Fighting is enabled (both weapons are Light weapons), so they make another attack; they attack with the Shadow Blade
5. Dual Flurry allows the character to make two attacks instead of one with two-weapon fighting; they use the Shadow Blade again

I'd like to rewrite the feat in such a way that the extra attacks enabled by Dual Flurry require the character to "balance out" the weapons they're using. Considering the example of a Fighter at various levels of play:

Fighter Level	Maximum Attacks Weapon A	Minimum Attacks Weapon B	Total Attacks
Level 1	1	1	2
Level 5	2	1	3
Level 5 (with Dual Flurry)	2	2	4
Level 11	3	1	4
Level 11 (with Dual Flurry)	3	2	5
Level 20	4	1	5
Level 20 (with Dual Flurry)	4	2	6

The problem I'm running into is that I'm struggling to come up with good, natural language that expresses this rule. I want the description of the feat to be intuitive and easy to understand, but not come across as clunky.

What would be a good way to rewrite this homebrew feat?

Answer 1

Dual Flurry

Prerequisite: Extra Attack

You can make two attacks instead of one with your bonus action from two-weapon fighting if you do not use the weapon for other attacks. All other conditions from two weapon-fighting still apply.

As you only have one bonus action, this will allow you to only attack twice in total. I think you might even be able to drop the second sentence, but with these homebrew feats it is often better to be verbose to make it clear what is meant.

I removed "or an equivalent feature" part, as that is undefined -- what is an equivalent feature to Extra Attack? If you have another feature in mind, I'd recommend to rather list that, but you can of course leave the Prequisite as you have it, if that is no issue for you.

Two-weapon fighting

It may be useful to recall the text from two weapon fighting, as that rule is referenced in the feat, to understand its conditions (p. 195 PHB):

When you take the Attack action and attack with a light melee weapon that you’re holding in one hand, you can use a bonus action to attack with a different light melee weapon that you’re holding in the other hand. You don’t add your ability modifier to the damage of the bonus attack, unless that modifier is negative. If either weapon has the thrown property, you can throw the weapon, instead of making a melee attack with it.

If it is important for you to be able to sequence the attacks so you could alternate main hand and off-hand (which you mentioned in a comment, although it is not in your question), my solution above will not work, as you only have the one bonus action and the bonus action's second attack would have to happen when you take it. In that case you could say

Once per turn, when you perform Two-Weapon Fighting, you can make an additional attack with the weapon you use for your bonus action attack as part of your Attack action. You cannot do so if you use the weapon for other attacks in your Attack action.

This would limit the additional attack to the off-hand weapon, and you could take it whenever you want.

The last sentence is there to take care of the set-up where you would first attack with another light weapon in your main hand, triggering two uses of your powerful off-hand weapon, and also use the weapon in your off hand for other attacks, either before or after that. A straightforward veto seems simplest to me, if you do not want that.

Note that the trick to hit repeatedly with the powerful off-hand weapon and only once with your main hand weapon still would work, as it has nothing to do with this feat, but without the added attack, it does not gain you anything vs just putting the strong weapon in your main hand.

Answer 2

Let them use TWF twice per turn

You can get the effect you want by allowing the character to use TWF twice in one turn, triggered by different attacks:

Dual Flurry

After you use your bonus action for Two-Weapon Fighting, you can use Two-Weapon Fighting one additional time that turn (no action required). Each use of Two-Weapon Fighting must be triggered by a different attack that you make as part of the same Attack action.

This forces the character holding 2 weapons to make a minimum of 2 attacks with each one when using this feat, but otherwise does not limit the the order of those attacks, and it gives them a lot of flexibility to choose which attacks to add their damage modifier to (useful if they know an enemy is very close to 0 HP). A level 20 fighter holding 2 weapons A & B could take the Attack action, make their 4 attacks with A, and then trigger TWF twice with 2 of those 4 attacks, making 2 attacks with B. Or they could use their Attack action to attack twice with A and twice with B, and then trigger TWF and either attack twice with one of the weapons or attack once with each one. They can even arbitrarily interleave TWF attacks with other attacks. For example, they can:

1. Take the attack action, making their first attack with A;
2. Use TWF to attack with B;
3. Continue their action, making their 2nd attack with B;
4. Use TWF to attack with A;
5. Finish their action, making 2 additional attacks with any weapon they're holding (even a third weapon that they draw or are holding in additional hands if they're a Thri-Kreen).

The fact that they are using TWF twice in one turn enforces that there must be 2 "pairs" of attacks that come from different weapons, which establishes the limitation you are looking for.

One very minor note is that the wording above intentionally requires both uses of TWF to be triggered by different attacks within a single Attack action. This implicitly requires Extra Attack or a similar feature, since this feat cannot be triggered by taking 2 Attack actions with one attack each (e.g. a character with 2 actions but no Extra Attack or similar feature). On the other hand, a 4th level Dread Ambusher ranger with this feat could technically use it on their first turn of combat. You could drop this requirement if you want to allow things like Action Surge to trigger the additional TWF use as well.

(Note: You mention in comments that you are removing the requirement to use a bonus action for TWF. In this case, you will obviously need to modify the above feat to avoid referring to bonus actions. I would recommend replacing the 1st sentence with the following, based on the wording of Extra Attack: "You can use TWF twice, instead of once, during your turn.")

Answer 3

If the number of attacks per weapon matters so much to you, then the most direct way is to engrave counting the number of attacks per weapon in the rule in the first place.

Dual Flurry

Prerequisite: Extra Attack, or an equivalent feature.

Once per turn, when you perform Two-Weapon Fighting, you may make two additional attacks instead of one. When making each attack, you must use one of the weapons you hold you have least attacked with in this turn, including with prior Dual Flurry attacks. If you have used two weapons you hold equally, you may choose which to use.

Since it counts the attacks in the turn per weapon, and forces the use of the least used weapon, it prevents "piling up" with a single (stronger) weapon.

The only way to be using the stronger weapon during Dual Flurry is to have used all weapons equally so far, or the weaker weapon more, in which case the pile-up has already been prevented.

Answer 4

You already require extra attack, use that fact.

Here's a wording that I think restpects your number of attack clause. The only thing I am doing is ensuring that the Dual Flurries are made with different weapon and that you have already committed to using both weapons :

Dual Flurry

Prerequisite: Extra Attack, or an equivalent feature.

When you perform two-weapon-fighting, if you attacked with both weapons as part of your Attack Action. You can make an attack with each weapon you are holding instead of only one of those weapons.

Did I miss something?

Two things I do not account for is characters with more than 2 arms. I'm not sure there are many-armed races that can attack with those arms. If there are, I trust the GM to make a ruling.

And my version does not allow the Dual Flurry between the first and second strike of the Standard Action. In my experience, I doubt this would be much of a problem compared to the simpler wording.

Answer 5

I've made similar feats and often find the easiest way to distinguish things is simply by considering a Main Hand and Off Hand attack. To me, most of this question, isn't about wording the feat for a wide audience but for someone who is clearly abusing it at a clearly homebrewed table.

Make it clear to the table that; the Attack Action uses the Main Hand attack while Two Weapon Fighting uses the Off Hand attack. Thus extra attack isn't Main then Off, or Left then Right. It is Left Left, if they then use Two Weapon Fighting, they can Right Right. Or if they Left Right Left Right. This doesn't NEED to be codified into rules until you intend to be published for outside your homebrewed group.

If you needed it codified for sharing beyond the setting where the DM can Rule as it is INTENDED, then simply put in the caveat:

... No arm can make more than one attack beyond that of another.

Thus Dual Flurry would read:

Once per turn, when you perform Two-Weapon Fighting, you may make two additional attacks instead of one. No arm can can make more than one attack beyond that of another.

Making 3 attacks with a single arm, whilst the short sword bearing arm makes 1 would offset and fail that caveat. This would also cover the potential arm issues of Tri-Keen's

Again, I think the clear solution is just talking to your player trying to abuse the system. YOU are clearly making an awesome setting for them to excel in, and they seem to still be abusing it.

Answer 6

This is probably the most straight-forward:

Dual Flurry

Prerequisite: Extra Attack, or an equivalent feature

Once per turn, while you've only attacked with a single weapon, when you perform Two-Weapon Fighting, you may make two additional attacks with the other weapon instead of one.

Since you want "Weapon B" to make at least 2 attacks, and Dual Flurry grants two, just make sure you haven't already used both. That makes it very clear which is going to be the "other weapon" to swing twice more.