Undying light warlock

[cZak]

Adds Charisma mod to fire & radiant damage effects.
If concentrating on Divine favor (+1d4 radiant damage) & cast Greenflame blade, does the secondary target get the Divine favor damage, and the Charisma boost damage?

Ex:
5th level warlock
(primary target) 1dx (weapon) + Str + 1d8 (fire) + Chr mod (fire) +1d4 (radiant) + Chr mod (radiant)
(secondary target of GFB) 1d8 (fire) + Chr mod (fire) +1d4 (radiant) + Chr mod (radiant)

[Belac93]

I believe you are talking about the Undying Light (from UA)? By the title, its very easy to confuse it with the Undying warlock (from SCAG).

[Arkhios]

Adds Charisma mod to fire & radiant damage effects.
If concentrating on Divine favor (+1d4 radiant damage) & cast Greenflame blade, does the secondary target get the Divine favor damage, and the Charisma boost damage?

Ex:
5th level warlock
(primary target) 1dx (weapon) + Str + 1d8 (fire) + Chr mod (fire) +1d4 (radiant) + Chr mod (radiant)
(secondary target of GFB) 1d8 (fire) + Chr mod (fire) +1d4 (radiant) + Chr mod (radiant)

I believe the design intent is for the radiant/fire damage bonus to apply only once when each spell deals damage, so while it would by my understanding apply to both Divine Favor and Green-Flame Blade, but not to both first and secondary targets of the cantrip.
Sage Advice precedent about Elemental Affinity (Draconic Sorcerer) says that the charisma only applies once to each spell, IIRC (I'm away from the source so I can't check, but you can find the Sage Advice Compendium as a free download)

[AstralFire]

My problem with the Sage Advice here is that it's completely inconsistent as the only time it does seem to work per individual attack is Eldritch Blast's Agonizing Blast, which has no special indicator that it should be treated differently.

IMO, the only spell that really needs to be treated differently is maybe Scorching Ray with everything else definitely getting the benefit per attack, and I get the feeling that's the usual mood around here.

[Arkhios]

My problem with the Sage Advice here is that it's completely inconsistent as the only time it does seem to work per individual attack is Eldritch Blast's Agonizing Blast, which has no special indicator that it should be treated differently.

IMO, the only spell that really needs to be treated differently is maybe Scorching Ray with everything else definitely getting the benefit per attack, and I get the feeling that's the usual mood around here.

That is a good point. However, I'd still prefer Sage Advice to Tweets as the "official" answer.
I think it should be more like: "applies to each instance of rolling damage with a spell." in which case it would mean that a fireball/lightning bolt gets the bonus damage once (since you roll the damage once), a scorching ray would deal the bonus damage each time a ray hits, chain lightning might get the bonus for each chain separately, etc. But that's just my opinion. The official statement, which I believe, is either Errata or Sage Advice.
Green-Flame Blade is a corner case, but technically, you roll the damage for second target immediately at the same time when you roll the damage for the initial target, in which case I would say it's still one instance of rolling damage.

[AstralFire]

"each instance of rolling damage with a spell" seems to refer to the same thing I meant -- an attack -- so we're on the same page there! (I'd consider GFB to be two attacks though).

Personally, the only cap I think needs to happen is that multiple sources of an attribute to a single attack (or single instance of rolled damage, whichever terminology one prefers) do not stack. So Shillelagh + GFB or Sacred Weapon gets no further benefit.

[cZak]

If the Chr boost comes from a different spell (ie, stacking GFB w Divine favor) would the boost apply to each spell application.

Because they are two diff damages (fire & radiant), seems to me they would

[Arkhios]

If the Chr boost comes from a different spell (ie, stacking GFB w Divine favor) would the boost apply to each spell application.

Because they are two diff damages (fire & radiant), seems to me they would

Uhh, yeah. That's what I thought I was saying. Might've said it more clearly, though.
Since they are indeed two different spells, Undying Light Warlock's charisma modifier applies to both spells separately (even if two spells did fire & fire, or radiant & radiant; as long as they come from different spells, both spells get the bonus; still, I'd say only once per GFB: Initial target would get extra +Charisma, while secondary wouldn't).

[Talanos]

How would Green Flame Blade work at lower levels when it only does secondary damage? Given an 18 CHA as the spellcasting stat, would it do 8 Fire damage instead of 4?

And then at 5th level, the bonus damage shifts to the primary target? 1d8+4 primary, 1d8+4 secondary?

Thanks.

[Hrugner]

If the Chr boost comes from a different spell (ie, stacking GFB w Divine favor) would the boost apply to each spell application.

Because they are two diff damages (fire & radiant), seems to me they would

Would it really work with divine favor? the language of radiant soul says "when you cast" not "when you deal damage with a spell". It seems worded only to work with spells that deal damage on casting.

[Gtdead]

All these different wordings...

ULW adds mod when you CAST a spell that DEALS DAMAGE. Once you cast the spell, you add the modifier. It's pretty clear. No matter how much damage the spell does and how it does it.
You cast fireball, it's 8d6+modifier
You cast gfb(lvl 17), its 3d8+4d8+modifier
You cast scorching ray, 6d6+modifier

If you cast a spell that doesn't deal damage, then you don't add the modifier. If you cast magic weapon, there is nothing to which you can add the modifier.
Same thing applies to Divine Favor

Compare it to Arcana Cleric's wording

You add the mod when you deal damage. That's a damn mess because we don't have a clear rule about what does "deal damage" means. Is it a precise rule or a guideline?
If you cast BB or GFB, you can potentially deal damage 2 times. The most sensible translation is that you have to add the mod every time you roll for damage. But where balance is concerned, this doesn't make much sense cause it's better than the other similar abilities.

And then we have Evoker Wizard's wording

A bit different than Arcana Cleric because here it's very precise wording. You add the modifier on the damage roll. So people were totally right to add it multiple times for a spell that deals multiple dice of damage. When really gets me, is that Errata isn't even a serious attempt to rework the ability. They just rule that you add it only once and then they decide to use similar wording again for Arcana Cleric.