What happens to a Chain Lightning spell with invalid primary target and valid secondary targets?

Question

This question asks what happens when a single-target spell has an invalid target. (A target that is not legitimately permissible, not a target that is weak from illness or injury).
The answer to that question appears to be: that depends on whether one wishes to implement an older Sage Advice segment of a Dragon Talk podcast, or the more recent but optional written rules in Xanathar's Guide to Everything.

Assume for this question that I prefer XGtE.

The optional rule for resolving invalid spell targets states (XGtE, p. 85-86):

If you cast a spell on someone or something that can’t be affected by the spell, nothing happens to that target, but if you used a spell slot to cast the spell, the slot is still expended.

Now consider the chain lightning spell, whose description says:

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

Suppose my primary target for the spell is invalid, because it is not a creature or an object. If an example must be given, suppose it is an illusion. However, each of the three secondary targets of the spell are valid, being either creatures or objects.

Do I spend the spell slot with nothing happening at all?
Or does the slot get spent as the chain lightning impacts the illusion but does nothing to it and then leaps to the three valid targets (with the full effects given in the spell description)?

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Note: I am assuming that an illusion is not an object, based largely on my interpretation that an illusion is not an "item" and on the text of the 14th-level School of Illusion wizard feature, Illusory Reality.

I am open to frame challenges that demonstrate that illusions are, in fact, objects - but such answers will be better if they then either provide a more appropriate example of something that is not a creature or an object, or demonstrate that the question is moot since everything is at least either a creature or an object.

Answer 1

I would definitely rule that the chain lightning continues on to its other targets. It does nothing to the invalid target (though in the case of the illusion this would be an “interaction” that could allow a save to see if you buy the illusion faking its reaction to being electrocuted), but the valid targets are affected exactly the same as they would be if the initial target is valid.

And frankly, if I was playing in a game where a DM ruled differently, I’d pretty strongly reconsider playing at that table.

It’s not that they don’t have a decent argument to make, based on the rules as written. It does say that it hits the initial target, and then continues on to the other targets. Xanathar’s does say that nothing happens to that target, which you could argue would include sparking the additional links in the chain. I’ve certainly played video games that have implemented things that way.

But I wouldn’t in D&D. It’s just finicky and counter-intuitive and an unnecessary “gotcha” moment. The game just does not need that. You’re already missing out on your primary attack, that’s a big loss. Compounding it by causing it to drop all the secondary attacks is just cruel, I think.

And arguing that “this is what the rules say!” is, I think, besides not really relevant—we care much more about a good game—also not totally accurate. The rules say that the spell does nothing “to” an invalid target. OK! Sure. Continuing on to target other individuals is not a thing done to the original target. Xanathar’s does not say that the spell fails as a whole, or that the invalid target is somehow no longer targeted—only that they aren’t affected. I think it’s a real stretch to nullify the rest of the spell on this basis. Not an impossible interpretation, but it is by no means a certain situation. And that only increases my feeling that ruling this way—bending over backwards to do so—is simply bad for the tables overall. You could rule that way, but you really, really don’t have to—and there’s a lot of good reasons why you shouldn’t.

Answer 2

This is a really good question, mainly because of player expectations as I will explain below.

The spell description answers your question:

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

The word "then" means that the prior condition is required. The last sentence specifies what is a valid target. The primary target isn't valid, so the first sentence never happens. If the first event never happens, the following event(s) don't either.

So, the corollary question is whether the spell would even reveal the illusion. The two rules quoted when combined say that it shouldn't. There is no "arc towards" and no "impact" occurring, so the caster may end up thinking the target has some weird immunity.

On the other hand, this will be difficult for the DM to do without confusing or even angering the players. If I was a player and my spell just fizzled without any clear cause, I'd be pretty annoyed! Even if it had to be explained afterwards, it'd feel like the DM was using an unfair and round-about method to punish my class choice.

On the other hand, if your players are already familiar with the strategy and concept, and they can do the same to enemy spell-casters (and succeed in doing so at some point), I think this would feel fair.

Answer 3

I would rule that the chain lightning has nothing to chain from, and thus does not chain to the secondary targets. The spell specifically states that the lightning arcs from the first target to the secondary targets, and there is no first target.

Answer 4

The spell does nothing

Per Xanathar's Guide, when casting at an invalid target:

If you cast a spell on someone or something that can’t be affected by the spell, nothing happens to that target, but if you used a spell slot to cast the spell, the slot is still expended.

An illusion (or totem) would be considered "something" (so no worry about creature/object debate). which means the chain lightning spell is cast and the spell slot is used, but nothing happens to the target.

The second part of the spell says:

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to ...

"Then" is a conditional statement meaning that something happened prior. In this case, your target was a phantom of some kind. But it cannot be a "target" as it was not a valid target to begin with, which means there is nothing to "leap from".

The last line of the first paragraph even says:

"A target can be a creature or an object and can be targeted by only one of the bolts."

So the spell description itself disqualifies the illusion from being a target from which bolts can leap.

Answer 5

Nothing stops you from casting chain lightning at an illusion.

"A target can be a creature or an object and can be targeted by only one of the bolts." "Can", not "must". Generally, a spell's target can be a creature, object, or point in space; chain lightning additionally requires that you see the target so you arguably couldn't target an empty point in space. But an illusion is an empty point in space that you can see.

Contrast a spell like fire bolt which says "You hurl a mote of fire at a creature or object".

(Before anyone asks, the second clause in that sentence is different: "can... only" implies that it is meant to be restrictive. It doesn't say "can only be a creature or an object".)

Answer 6

Nothing happens, but the spell slot is still expended

From XGtE, pg. 85-86 "Invalid Spell Targets"

If you cast a spell on someone or something that can’t be affected by the spell, nothing happens to that target, but if you used a spell slot to cast the spell, the slot is still expended. If the spell normally has no effect on a is target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn’t attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Nothing happens to the illusion, and you expend a spell slot.

You create a bolt of lightning that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

It requires the bolt of lightning to strike the primary target, and the primary target is invalid. So, no lightning bolts leap to any additional targets, since there was no "first target."

However..

A benevolent DM may rule that the lightning continues through that creature until it strikes another object or creature, and consider that the primary target of the attack; but doing so would be a house rule.

In conclusion..

By RAW, an illusion is an invalid target for any spell, so it cannot be the target of chain lightning. The spell specifically names the target as the origin of the secondary lightning bolts, but lightning never struck the illusory target in the first place.

Answer 7

Expanding upon the excellent answer by @Kryan.

The paragraph by XGTE actually states the answer, so let's reiterate with emphasis on the important wording.

If you cast a spell on someone or something that can’t be affected by the spell, nothing happens to that target [...] If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn’t attempt one [...] Otherwise, you perceive that the spell did nothing to the target.

Therefore by the rules of the game - the lightning bolt arch towards the target and does nothing. Then three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target.

One may house rule that the arch instead passes directly through the illusion, and thus misses, but nothing in the spell description nor the ruling at XGTE states that the bolt misses the target, forfeiting the preceding effects.

Answer 8

No effect at all, no chaining, nothing the spell is wasted.

As per Spell casting and targets requirement are intentional and strict. THis is documented in the PHB and was further confirmed in the Sage Advice compendium

Spells cannot effect in any ways invalid targets, if you do cast a spell at an invalid target (either because you think it is a valid one but actually an illusion or some other reasons)

Supporting Evidence by the game designer supporting my concluions and that this is what the designer intended.

• https://www.reddit.com/r/dndnext/comments/5ozpwj/jeremy_crawford_on_targeting_spells/
• https://twitter.com/JeremyECrawford/status/931621590730653696

Note: if unsure what 'suppressed' means, game designers indicate it is what a normal english dictionary says it means.

Ref: XGE Rule book page 85 (copied below)

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A spell specifies what a caster can target with it: any type of creature, a creature of a certain type (humanoid or beast, for instance), an object, an area, the caster, or something else. But w hat happens if a spell targets something that isn't a valid target? For example, someone might cast charm person on a creature believed to be a humanoid, not knowing that the target is in fact a vampire. If this issue comes up, handle it using the following rule. If you cast a spell on someone or something that can't be affected by the spell, nothing happens to that target, but if you used a spell slot to cast the spell, the slot is still expended. If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact a n invalid target). Otherwise, you perceive that the spell did nothing to the target

So in Conclusion

the spell has no effect and is lost. So there would not even be lightning launched at the illusion in the first place, let alone the possibility to chain it somewhere else.

It would at least indicate that this is not what you think it is and allow you a second saving throw against the illusion with likely advantage to the save.

Answer 9

Spells do what they say they do, no more and no less

Say you were casting chain lightning at a "creature" which was actually just the product of a major image spell. The major image spell description has the specific details about how you can determine that it is an illusion:

Physical interaction with the image reveals it to be an illusion, because things can pass through it. A creature that uses its action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the creature can see through the image, and its other sensory qualities become faint to the creature.

The options for revealing it is a fake are listed there. Having a spell fail because you aren't targeting a real thing isn't amongst them.

As such, your chain lightning will appear to strike the illusion, then continue on the the secondary targets.

Answer 10

The key word in the spell is target.

You create a bolt of lightning that arcs toward a target of your choice that you can see within range.

...

Three bolts then leap from that target to as many as three other targets.

...

A target can be a creature or an object and can be targeted by only one of the bolts.

This pretty clearly defines everything affected by the spell, including the initial part of the spell, as a target, and very importantly, that the target must be a creature or an object.

As a DM, I would rule that an illusion is neither a creature nor an object, and therefore not a valid target - assuming your character believes the illusion is real (which I would call a saving throw for before the spell is cast), the spell would be expended, but find no purchase on the initial target of the spell, wasting the spell slot as per XGte (Meaning - it would not affect the additional targets afterwards).

However, as with most rulings, the final say is up to DM discretion.