Can the Twinned Spell metamagic be used on a spell cast as a reaction from the War Caster feat?

Question

I'm not sure if this interpretation of RAW is correct or if there is any RAI that would decide if twinning a warcast spell is valid. Is there anything that makes it explicit that a single target spell cast through the War Caster feat can or cannot be twinned?

War Caster

When a hostile creature's movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, instead of making an opportunity attack. The spell must have a casting time of only 1 action and must target only that creature.

From what I can tell, War Caster takes place during the triggering of the reaction. You replace a opportunity attack with the casting of a spell, or essentially the Cast Spell action. Once you select a spell that takes 1 action and is targeting only the creature that has provoked the Reaction, the requirements of War Caster are satisfied.

Metamagic: Twinned Spell

When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip).

Based on the phrasing of this metamagic feature, you select to twin a spell after you have selected targets. That would be after War Caster's conditions have already been met.

Now, Twinned Spell does not work on things like Fire Ball, because it can target more than one creature, even if it currently doesn't. I'm not sure if this can be applied to War Caster in the same way though, because what is causing that to be the case is Twinned Spell. And if you can't use something like Fire Bolt because it could be twinned and that makes it violate the condition "must target only that creature" that would imply that you can't twin Fire Bolt ever because "that targets only one creature" would also apply. So if you can't twin a warcast spell, you shouldn't be able to twin any spells, from what I can tell. That leads me to conclude that you must be able to twin a warcast spell. Twinned Spell does not apply retroactively to itself, so it would make sense it doesn't apply retroactively to War Caster.

What information exists that makes this clear and less reliant on just trying to guess the order of operations for when War Caster's condition stops applying?

Answer 1

Probably not

You select the Twinned Spell target at the same time you select your primary target for the spell from War Caster. It says "When" you cast the spell. In other words, there are not two rounds of target selection, only one.

You can cast a spell that does not require an attack roll, but I think looking at the rules for making an attack helps reinforce this interpretation:

1. Choose a target. Pick a target within your attack's range: a creature, an object, or a location.

2. Determine modifiers. The DM determines whether the target has cover and whether you have advantage or disadvantage against the target. In addition, spells, special abilities, and other effects can apply penalties or bonuses to your attack roll.

3. Resolve the attack [...]

Set aside the question of whether or not twinning is allowed for a second. The reaction is resolved by first declaring targets (at this point, the caster would pay the sorcery point(s) to add a second target if it were allowed), determine what sort of bonuses or penalties each roll would make, and then roll the dice to make the spell attack.

Obviously, the spell might not involve an attack roll, in which case the latter steps are skipped (or they apply to the target if it needs to make a save).

But we see only one round of target selection because it's one spell. Twinning just gives the caster the option of expanding that selection to more than one target, but War Caster precludes selecting more than one target for the spellcasting. All this is established before the spell's effect is resolved and the casting is finished.

So I think the rules indicate that one can't twin a spell cast using the War Caster feat.

Answer 2

No

War Caster only allows you to use your reaction to cast a spell at the creature that provoked an opportunity attack. Twinned Spell allows you to cast the spell at a second target. You could twin the spell, but War Caster does not allow you to cast the spell at any other target than the creature that provoked the opportunity attack.

You argue that twinning a spell doesn't disqualify it from Twinned Spell, because if that was the case you could never twin anything. I disagree. Fire bolt can be twinned, but twinning it does disqualify it from Twinned Spell, since you can't twin a Twinned fire bolt. You can twin it, but once twinned you can not twin it a second time. Twinning a spell also disqualifies it from use with a War Caster reaction.

Fire bolt is valid for both Twinned Spell and War Caster, but a Twinned fire bolt is valid for neither.

Answer 3

You cannot use the Twinned Spell Metamagic on a spell cast using the War Caster feat

The War Caster feat states:

[...] The spell must have a casting time of only 1 action and must target only that creature.

This phrase has no time restriction, the entirety of that spell must target only that one creature. It does not say that the spell must only target one creature at that time it must simply only target one creature, end of sentence. This prevents you from adding more targets to the spell through the Twinned Spell Metamagic option.

Answer 4

RAW, there isn't a lot of thing to either validate or counter this. But your logic is good.

I add a bit of a hard time to understand your point but this is a really good question.

To clarify a bit, the Twinned Spell effect is :

• When you cast a spell -with the restriction of being mono-target-, you can add the Twinned Spell effect to it.

• If you choose to do so, the spell isn't mono-target anymore and therefore doesn't pass the restriction anymore.

So it seems like the limits only apply when the spell is chosen and don't retroactively check the validity of the spell.

If we apply the same logic for the Warcaster feat effect, once the spell is chosen, the limits shouldn't be re-check so if you choose to apply Twinned Spell, it should work.

Answer 5

Not Allowed Due to Targeting Contradiction

If its any consolation, I'd ok it as a DM. However, when considering RAW there's a contradiction between targeting restrictions. War Caster says only that creature while Twinned Spell says target a second creature. Since metamagic shapes the same spell - that spell cannot both target only one creature and also target a second creature.

Metamagic reads:

At 3rd level, you gain the ability to twist your spells to suit your needs...

Also, Twinned Spell reads:

...target a second creature in range with the same spell...

Therefore, both processes concern the same spell. War Caster requires that the spell must only target that creature. Twinned Spell targets a second creature within range and uses the same spell.

In other words:
A.) War Caster requires only that creature to be targeted
B.) Twinned Spell uses the same spell (i.e. doesn't duplicate effects or create a new spell)
C.) Twinned Spell requires a second creature in range

A & C are a contradiction - meaning that both cannot occur.