Grim Hollow Feat "Lightning Caster"

So it goes as so. 

Technically, if you target all the beams at 1 creature, you can target a second creature once as a Bonus Action. You are getting an additional target, not an additional casting of the spell.

I agree. It's technically legit, and the second creature would receive only one beam.

I think we can find an equivalent interaction with War Caster + Eldritch Blast. I shared this in a thread about the War Caster feat:

Quote from Tarod_ >>

While not official ruling, this is from the Dev:

@thomas_conners Can warcaster be used to cast a lvl 5+ Eldritch Blast as long as all the rays target only the provoking creature?
@JeremyECrawford Yes

I admit I agree with that.

Like a lot of homebrew stuff, this is badly written and open to many possible interpretations. 
It doesn't say if you make another attack roll, it doesn't say if saving throw cantrips work, it doesn't say if you roll the damage once or twice, and it doesn't give any indication on how to handle the special case of Eldritch Blast.
So... anything goes, really. It's between you and the DM :)

If I was the DM in this case, I would say that it doesn't work at all. I would interpret "a cantrip with a casting time of an action that targets a single creature" as a cantrip that can only target a single creature. If it's an attack roll, make another attack and damage rolls, and if it's a saving throw, roll 2 instances of damage.
Eldritch Blast is busted enough as it is :)

Quote from Natrel >>

Like a lot of homebrew stuff, this is badly written and open to many possible interpretations. 

It's third party, a step up from homebrew. As with all third-party content, the quality varies. I believe this publisher has a reputation for being one of the better ones though.

Quote from Natrel >>

It doesn't say if you make another attack roll, it doesn't say if saving throw cantrips work, it doesn't say if you roll the damage once or twice, and it doesn't give any indication on how to handle the special case of Eldritch Blast.

I think all of that is pretty obvious. Essentially, it's expending a Bonus Action while you cast the spell to increase the targets, similar to the 2024 Twinned Spell metamagic. Unlike Twinned Spell, it applies to Cantrips and just gives you an extra target. At level 17, you can Firebolt two targets for 4d10 damage for a Magic Action and a Bonus Action.

Now, if someone triggers an Attack of Opportunity on your turn and you use your reaction to cast a cantrip at that creature, can you still use this to target a second creature?

Quote from Rationale01 >>

So it goes as so. 

Ability Score Increase. Increase your Int, Wis, or Cha score by 1, to a max of 20.

Dual Target. When you cast a cantrip with a casting time of an action that targets a single creature, you can use a Bonus Action to target a second creature within the cantrip's range.

Immediate Response. Once per Long Rest, when you cast a spell as a Reaction, that spell doesn't expend a spell slot.

Simple question here. I'm using Eldritch Blast at 11th level. 3 blasts per casting. Does this mean:

I must target all 3 beams at 1 creature, and then hit another creature with 3 beams ( I must roll 6 times)

or

I can target three creatures ( a single creature per blast), and therefore target 3 other creatures within range.'

or

Some other interpretation.

What say you DnD community. My DM and I have already discussed. But would like to see how other DM's rule on this. 

 

 

The established interpretation from the 2014 Twinned spell days, which is what this feat seems to be echoing, is that it would need to be a spell that doesn't even give you the option of targeting multiple creatures

Under that interpretation, EB wouldn't be eligible for the feat at all

Quote from AntonSirius >>

The established interpretation from the 2014 Twinned spell days, which is what this feat seems to be echoing, is that it would need to be a spell that doesn't even give you the option of targeting multiple creatures

Under that interpretation, EB wouldn't be eligible for the feat at all

I disagree. This feat is closer to War Caster than the old Twinned Spell metamagic because it lacks the restriction that Twinned Spell had.

Quote from Rationale01 >>

Dual Target. When you cast a cantrip with a casting time of an action that targets a single creature, you can use a Bonus Action to target a second creature within the cantrip's range.

2014 Twinned Spell. The similarity to the first paragraph is irrelevant as that does not restrict spells that can target the same creature multiple times or multiple creatures. Eldritch Blast is only restricted with the second paragraph.

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).

To be eligible, a spell must be incapable of targeting more than one creature at the spell's current level. For example, magic missile and scorching ray aren't eligible, but ray of frost and chromatic orb are.

War Caster

Reactive Spell. When a creature provokes an Opportunity Attack from you by leaving your reach, you can take a Reaction to cast a spell at the creature rather than making an Opportunity Attack. The spell must have a casting time of one action and must target only that creature.

Quote from SmiteMakesRight_3_5>>

Quote from AntonSirius>>

The established interpretation from the 2014 Twinned spell days, which is what this feat seems to be echoing, is that it would need to be a spell that doesn't even give you the option of targeting multiple creatures

Under that interpretation, EB wouldn't be eligible for the feat at all

I disagree. This feat is closer to War Caster than the old Twinned Spell metamagic

 You're literally targeting a second creature with the same spell

Quote from SmiteMakesRight_3_5 >>

I think all of that is pretty obvious. Essentially, it's expending a Bonus Action while you cast the spell to increase the targets, similar to the 2024 Twinned Spell metamagic. Unlike Twinned Spell, it applies to Cantrips and just gives you an extra target. At level 17, you can Firebolt two targets for 4d10 damage for a Magic Action and a Bonus Action.

Now, if someone triggers an Attack of Opportunity on your turn and you use your reaction to cast a cantrip at that creature, can you still use this to target a second creature?

 
Yes, but like you mentioned, only if you take that Reaction during your turn. And while this might feel like it contradicts War Caster, you only take that Bonus Action after casting the cantrip.

The rest is obvious to you, maybe. But the only thing "common" about common sense is that everybody believes they have it. "Obvious" is, more often than not, a very subjective opinion. Especially when we try to infer the intent behind a rule.

This is why rules should be worded in ways that minimize the number of edge cases (which is easier said than done), and cover the unavoidable ones when several interpretations are possible.
And do all that while keeping the description clear and concise. That takes professional skill. And while partnered content often meets that bar, it still tends to miss it much more often than official content. That's why I tend to put it in the same basket as homebrew, even though it's indeed a step up.

Quote from AntonSirius >>

Quote from SmiteMakesRight_3_5>>

Quote from AntonSirius>>

The established interpretation from the 2014 Twinned spell days, which is what this feat seems to be echoing, is that it would need to be a spell that doesn't even give you the option of targeting multiple creatures

Under that interpretation, EB wouldn't be eligible for the feat at all

I disagree. This feat is closer to War Caster than the old Twinned Spell metamagic

You're literally targeting a second creature with the same spell

You have the option to target a second creature, but you are not required to and can target the same creature with all attacks.

The text that is similar between the 2014 Twinned Spell and Lightning Caster does not restrict selecting spells that have the potential of targeting a second creature. That is the second paragraph of the 2014 Twinned Spell which is not present here. Because of that, the comparison is invalid and War Caster is more appropriate.

While it didn't make it into the Sage Advice documents, Jeremy Crawford has said that Green Flame Blade is valid to use with War Caster if the caster chooses not to target a second creature. Now, his interview isn't considered RAW, of course, but it does indicate RAI and is a valid interpretation of War Caster that is also applicable here.

Quote from SmiteMakesRight_3_5 >>

Quote from AntonSirius >>

Quote from SmiteMakesRight_3_5>>

Quote from AntonSirius>>

The established interpretation from the 2014 Twinned spell days, which is what this feat seems to be echoing, is that it would need to be a spell that doesn't even give you the option of targeting multiple creatures

Under that interpretation, EB wouldn't be eligible for the feat at all

I disagree. This feat is closer to War Caster than the old Twinned Spell metamagic

You're literally targeting a second creature with the same spell

The text that is similar between the 2014 Twinned Spell and Lightning Caster does not restrict selecting spells that have the potential of targeting a second creature. That is the second paragraph of the 2014 Twinned Spell which is not present here. Because of that, the comparison is invalid and War Caster is more appropriate.

As you helpfully pointed out already, the text of Lightning Caster isn't the same as either 2014 Twinned or any version of War Caster, so as a RAW argument, that's a complete non-starter. "It's not the same as this thing, but it's also not the same as that thing" tells us... nothing, really

If you want to read the absence of language as a clue toward RAI, you're welcome to do so, but in this case you then run into the same issues that the original language in 2014 Twinned was trying to head off, and which are the entire reason this thread exists

Dual Target. When you cast a cantrip with a casting time of an action that targets a single creature, you can use a Bonus Action to target a second creature within the cantrip's range.

"Target a second creature" with... what? The whole spell again? A single attack? Treating it as a similar feature to 2014 Twinned at least provides some guidance on how to answer that

FWIW, the original text from the 2020 edition of the feat, prior to it getting a 5.5 update, makes the Twinned similarity clearer

Lightning Caster - The ability to cast at least one cantrip - Your rapid-fire style of casting cantrips allows you to weave magic with uncanny speed, granting you the following benefit:

Whenever you cast a cantrip that can only target a single enemy, you can use your bonus action to target two enemies within 5 feet of one another instead.

Quote from AntonSirius >>

FWIW, the original text from the 2020 edition of the feat, prior to it getting a 5.5 update, makes the Twinned similarity clearer

Lightning Caster - The ability to cast at least one cantrip - Your rapid-fire style of casting cantrips allows you to weave magic with uncanny speed, granting you the following benefit:

Whenever you cast a cantrip that can only target a single enemy, you can use your bonus action to target two enemies within 5 feet of one another instead.

So, it appears that the updated version was deliberately changed to remove the restriction to spells that are only capable of targeting a single enemy and the comparison to 2014 Twinned Spell is more invalid.

Quote from SmiteMakesRight_3_5 >>

Quote from AntonSirius >>

FWIW, the original text from the 2020 edition of the feat, prior to it getting a 5.5 update, makes the Twinned similarity clearer

Lightning Caster - The ability to cast at least one cantrip - Your rapid-fire style of casting cantrips allows you to weave magic with uncanny speed, granting you the following benefit:

Whenever you cast a cantrip that can only target a single enemy, you can use your bonus action to target two enemies within 5 feet of one another instead.

So, it appears that the updated version was deliberately changed to remove the restriction to spells that are only capable of targeting a single enemy and the comparison to 2014 Twinned Spell is more invalid.

You are free to project whatever interpretation you want onto that change

You still have no answers to the problems that creates, though

Quote from AntonSirius >>

You still have no answers to the problems that creates, though

The problems are imaginary.