[RPG] Can the Green-Flame Blade cantrip be cast as a reaction using the War Caster feat


The War Caster feat (PHB, p. 170) allows a single-target spell ("must target only that creature") to be cast instead of an opportunity attack.

The Green-Flame Blade cantrip (SCAG, p. 142) appears to have a single target, and then some damage "leaps" onto a creature 5 feet away. The other creature is never referred to as the target, or even "a target".

Can the Green-Flame Blade cantrip be cast as a reaction using the War Caster feat?

I'm pretty sure this is solid from the RAW perspective. Is this legit from a RAI perspective?

Best Answer

The RAI on this one is a little uncertain, from what I can tell.

In this October 2015 tweet, rules designer Jeremy Crawford responded to a question about using the Green-Flame Blade cantrip for an opportunity attack:

Without a feature like the War Caster feat, a spell can never be cast in place of an opportunity attack.

He doesn't make it incredibly clear, but the implication here seems to be that with the feat, this would be possible.

However, this is contradicted by a later tweet in November 2015, in which he stated:

Twinned Spell doesn't work with a spell that targets more than 1 creature. Green-flame blade targets 2.

This explicitly states that the spell targets multiple creatures (and therefore wouldn't qualify for the War Caster benefit), but again in a different context.

My instinct here is to agree with explicit disqualification, rather than implied exception, so I would say the RAI is that you can't use Green-Flame Blade with an opportunity attack.