Flames of Phlegethos: does the fire spell need to actually deal damage?

[Greywander]

This is a tiefling racial feat from Xanathar's, in case the name doesn't ring a bell.


Whenever you cast a spell that deals fire damage
Does this mean that the spell actually has to deal fire damage when the spell is cast, or only that the spell be capable of inflicting fire damage?

I mean, it could have said, "Whenever you deal fire damage with a spell," or, "Whenever cast a spell and deal fire damage with that spell."

Obviously, there's the question of, "What if I miss with the spell and don't deal damage?" But then there's also a spell like Produce Flame, which is capable of dealing fire damage, but doesn't require you to attack when you cast it. That last effect (of the feat) is pretty niche and not super useful, but I'm still curious how exactly it triggers.

I'm also curious how people think this feat measures up to Elemental Adept. Being a half feat is nice, and the rerolls provide more damage than simply treating 1s as 2s. It seems like it would depend on how many enemies are resistant, but not immune, to fire damage. Of course, if you have the ASIs to spare, you could get both.

[Galithar]

I would say that the ability should activate if the spell is capable of dealing damage in the manner it was cast.

What I mean by that is Produce Flame doesn't deal damage unless the flame is thrown. I probably would trigger the feat when the Flame is thrown. (Some may disagree with this because it also says 'when you cast a spell that...' and technically if you cast Produce Flame and then wait to throw it, it wasn't cast when you dealt the damage)

Another example is Chromatic Orb. It would trigger is you chose fire as the damage type, even if the attack misses. But it wouldn't trigger is you choose acid just because the spell is capable of dealing fire damage, your casting wasn't.

[LudicSavant]

My ruling would be that the third bullet point of Flames of Phlegethos activates at the moment of casting, not when it actually deals fire damage.

[Chronos]

A Produce Flame that you haven't thrown yet, or similarly a Wall of Fire that nobody's walked through yet, is still a spell that deals fire damage, and you've cast it. A Chromatic Orb set to cold isn't a spell that deals fire damage.

I'm unsure about a summoning spell that summons a fire elemental. It feels like it shouldn't work, but I'm having a hard time distinguishing it from the Wall of Fire.

[Galithar]

A Produce Flame that you haven't thrown yet, or similarly a Wall of Fire that nobody's walked through yet, is still a spell that deals fire damage, and you've cast it. A Chromatic Orb set to cold isn't a spell that deals fire damage.

I'm unsure about a summoning spell that summons a fire elemental. It feels like it shouldn't work, but I'm having a hard time distinguishing it from the Wall of Fire.

I would rule no on the elemental. The spell doesn't deal for damage. It summons a fire elemental. The fire elemental deals fire damage. (I would probably rule differently if the spell was "Summon Fire Elemental")