D&D 5E Magic Missile vs. Mirror Image

[Cognomen's Cassowary]

And the b(l)eat goes on. . . .

 

[Lord Twig]

It can be a perfectly internally consistent ruling, but it cannot be based on the RAW while RAW says that it can only target a creature and your rule allows it to target things that are not creatures.

I fully admit I stray into house rule territory, but if you think my ruling isn't based on RAW, I'm curious what you think the RAW actually is.

If a Wizard targets an enemy with a Magic Missile and that enemy turns out to be an illusion. What happens? Is he just physically incapable of pointing at the illusion? Does a magical force stop him from chanting the spell?

Think of it this way. Let's say the Fighter is blinded and wants to attack an enemy with his longsword. He thinks the enemy is right next to him, but the enemy is actually 10' away, and therefore not a valid target. Can the Fighter not make that attack? Does an invisible force stop him from swinging his sword? I rule that the Fighter attacks, but it automatically fails since the enemy he was trying to hit is not a valid target. Same thing for the Magic Missile.

My ruling is that you can't target non-creatures with a Magic Missile, so if you try, the spell fails. How it fails is my own ruling, since it is left vague in the RAW. So how is that not based on RAW?

Like I said, I'm perfectly happy ignoring the RAW and will keep my rule because it "makes sense" to me, but am curious why you think it isn't based on RAW.

 

[Ovinomancer]

And the b(l)eat goes on. . . .

Baa. Not an argument.

 

[ThePolarBear]

1) If a Wizard targets an enemy with a Magic Missile and that enemy turns out to be an illusion. What happens? Is he just physically incapable of pointing at the illusion? Does a magical force stop him from chanting the spell?

2) Let's say the Fighter is blinded and wants to attack an enemy with his longsword. He thinks the enemy is right next to him, but the enemy is actually 10' away, and therefore not a valid target.

3) My ruling is that you can't target non-creatures with a Magic Missile, so if you try, the spell fails. How it fails is my own ruling, since it is left vague in the RAW. So how is that not based on RAW?

Numbers added by me, for simplicity

In my opinion:

1) I like your previous post interpretation. Just add that the puzzled Wizard rolls investigation because it interacted with the illusion. If not passed, they rationalize. Still, i feel bad for those poor Mimics, blasted by cantrips before doing their job. I would really like to avoid the "might be a mimic" check at my table.

2) Not really a fair comparison. Rules are clear, fighter has to guess before attacking. Specific beats generic. If the fighter attacked an illusion, same as above and roll investigation/auto succes. Also, the fighter can attack an object or an illusion by rules, a Magic Missile can't be targeted at one. Again, not really a fair comparison.

3) Fair. But i would warn the player beforehand if his character has knowledge that the spell would fizzle. A player might not remember that eldritch blast can only target creatures if he tries to blast a lock. But with Mirror Images you can't distinguish one image from the other. So you can't decide "one each" since you don't know which is which.You still see the creature, and Magic Missile is Magic enough to hit the right target. Or passes all the images and end up hitting the target. There's no roll, so ruling from Mirror Images still applies. So the point is moot, at least for Mirror Images.

Al imho.

 

[Lord Twig]

Numbers added by me, for simplicity

In my opinion:

1) I like your previous post interpretation. Just add that the puzzled Wizard rolls investigation because it interacted with the illusion. If not passed, they rationalize. Still, i feel bad for those poor Mimics, blasted by cantrips before doing their job. I would really like to avoid the "might be a mimic" check at my table.

2) Not really a fair comparison. Rules are clear, fighter has to guess before attacking. Specific beats generic. If the fighter attacked an illusion, same as above and roll investigation/auto succes. Also, the fighter can attack an object or an illusion by rules, a Magic Missile can't be targeted at one. Again, not really a fair comparison.

3) Fair. But i would warn the player beforehand if his character has knowledge that the spell would fizzle. A player might not remember that eldritch blast can only target creatures if he tries to blast a lock. But with Mirror Images you can't distinguish one image from the other. So you can't decide "one each" since you don't know which is which.You still see the creature, and Magic Missile is Magic enough to hit the right target. Or passes all the images and end up hitting the target. There's no roll, so ruling from Mirror Images still applies. So the point is moot, at least for Mirror Images.

Al imho.

I'll stick with the numbers...

1) I like the addition of an Investigation check. It adds more use to that skill. So I'm going to use that.

As for the cantrips Acid Splash, Eldritch Blast and Ray of Frost target creatures. Fire Bolt targets a creature or object. I could say that Acid Splash and Ray of Frost hit objects and do nothing, just like I rule for Magic Missile, but this seems odd to me. Since they are elemental spells, I will probably allow Acid Splash, Fire Bolt and Ray of Frost to effect creatures, objects or locations, just like an attack. I'm on the fence about Eldritch Blast. It is a force effect, like Magic Missile, but it requires an attack roll like Fire Bolt or Ray of Frost. But this is firmly in house rule terrain. If I wanted to stick closer to RAW I would just have them work the same as Magic Missile.

2) I probably just muddied the waters with this example and should have left it out. You are right, there are specific rules for attacks against invisible creatures and they can target locations. But the fact that spells have no such rules means that you have to make a ruling in the rule's absence. Based on my interpretation of the RAW I made my own ruling.

3) Oh absolutely. I would inform the caster of how his spells would interact with invalid targets in advance.

If I understand correctly, your interpretation is that you target the enemy with Mirror Image and the Magic Missile spell, since it automatically hits, ignores the images and hits the target with all missiles? That's a fair ruling. I would be perfectly content as a player if my DM went that way. Honestly this might be the correct way by the strictest reading of the RAW.

I guess I am influenced by past editions where you would actually roll to see which image you hit. Since Magic Missile hits everything simultaneously, none of the images could move before all of the missiles hit. Likewise any spell with a duration of instantaneous would hit so fast that there wouldn't be time for the images to move. But again this probably falls into a house rule, but I'm fine with that.

What I don't believe falls into a house rule is targeting spells against invalid targets. If a spell says you can only target creatures and you target an object, the spell fails because the target is invalid. I don't believe the RAW implies you are just incapable of casting the spell.

Consider another example. What happens if you cast Hold Person on a dragon that is Polymorphed into a human? I would rule that you cast the spell and it failed to work. The caster might just assume that the target made their save. Or I might allow a Spellcraft or Investigation check to realize that the target isn't actually human, depending on the situation.

 

[firstkyne]

At this point in 5E's run, I'm willing to place money on Jeremy Crawford consistently ruling ass-backwards.

Yeah, there's an increasing number of things he has said in a tweet that I have totally disagreed with. Going back on RAW and really complicating things in the process is not cool. In those cases, people quoting it on this forum with a 'so that's the end of it!' sort of tone is getting really tiring. (Not referring to anyone in this particular discussion, btw).

 

[Sword of Spirit]

Consider another example. What happens if you cast Hold Person on a dragon that is Polymorphed into a human? I would rule that you cast the spell and it failed to work. The caster might just assume that the target made their save. Or I might allow a Spellcraft or Investigation check to realize that the target isn't actually human, depending on the situation.

This is a great precedent for how to handle damaging spells against invalid targets. I think pretty much everyone would rule that such a spell does get cast, it just doesn't do what it's supposed to (ie, affect the chosen target). That could work just as well for damaging spells--they get cast, and they fly towards the intended target, they just fail to affect it.

 

[Arial Black]

I fully admit I stray into house rule territory, but if you think my ruling isn't based on RAW, I'm curious what you think the RAW actually is.

If a Wizard targets an enemy with a Magic Missile and that enemy turns out to be an illusion. What happens? Is he just physically incapable of pointing at the illusion? Does a magical force stop him from chanting the spell?

Think of it this way. Let's say the Fighter is blinded and wants to attack an enemy with his longsword. He thinks the enemy is right next to him, but the enemy is actually 10' away, and therefore not a valid target. Can the Fighter not make that attack? Does an invisible force stop him from swinging his sword? I rule that the Fighter attacks, but it automatically fails since the enemy he was trying to hit is not a valid target. Same thing for the Magic Missile.

My ruling is that you can't target non-creatures with a Magic Missile, so if you try, the spell fails. How it fails is my own ruling, since it is left vague in the RAW. So how is that not based on RAW?

Like I said, I'm perfectly happy ignoring the RAW and will keep my rule because it "makes sense" to me, but am curious why you think it isn't based on RAW.

Well, my reasoning was in my quote!

But I can see your dilemma in cases where the caster believes something to be an acceptable target, but isn't.

So what does 'target' mean in this context? I don't think it means that the spell cannot be cast, because that means you could use these spells as infallible creature detection devices that don't even cost a slot if the target wasn't a creature. Poor mimics, evolution failed you!

I think it means that if the thing that you aimed at is not a valid target for that spell, then that spell does not affect it in any way. So you could eldritch blast the lock, but it would not damage the lock (or push it back 10 feet!) because the lock is not a valid target.

When someone is protected by mirror image, in 5E there are not four targets; there is one target who could be in any of four positions. It's like Schrodinger's target; the guy is in all of those places, until you 'observe' him by an attack roll. Magic missile is blind and so ignores the effect of MI, unerringly striking the target no matter where he actually is, without reducing the effectiveness of the quantum uncertainty that is mirror image.

 

[Yunru]

It's rather comical that you accuse him of making the same mistake you are guilty of in this very thread. See above.

Difference is people don't try and use my word as gospel.

 

[ThePolarBear]

1) If I understand correctly, your interpretation is that you target the enemy with Mirror Image and the Magic Missile spell, since it automatically hits, ignores the images and hits the target with all missiles? That's a fair ruling. I would be perfectly content as a player if my DM went that way. Honestly this might be the correct way by the strictest reading of the RAW.

I guess I am influenced by past editions where you would actually roll to see which image you hit. Since Magic Missile hits everything simultaneously, none of the images could move before all of the missiles hit. Likewise any spell with a duration of instantaneous would hit so fast that there wouldn't be time for the images to move. But again this probably falls into a house rule, but I'm fine with that.

2) What I don't believe falls into a house rule is targeting spells against invalid targets. If a spell says you can only target creatures and you target an object, the spell fails because the target is invalid. I don't believe the RAW implies you are just incapable of casting the spell.

New numbers!

1) It's not the complete idea, but yes. Your target is still the caster of Mirror Image, anyways. In older editions, Mirror Images were not explicitly bound behind an attack, as defined in 5e. You (well, the caster of MI) still rolls to see if is he getting hit or not. Also, some older versions of MI required the caster to move to actually regain the "roll to be missed" that MI confers once people knew which one was the real one...

I would not allow instant spell (that require a roll) or... well... anything that does not directly counters illusions to distinguish between images and "real", since is explicitly stated that "it's impossible to track which image is real" (strange concept... again). The spell would appear to hit something, and either dismiss AN image (not necessarly the one you hit, not that you could distinguish it...) or not. You would be right to say that in the second case, you missed. Your target i mean. The caster.

2) I gave a second read to the "Targets" section of "Spellcasting"... It tells that you have to pick a target TO AFFECT, and that spells lists which targets it can... target. Honestly? I think i'll use your interpretation, since the player chooses the target to affect, and the spell tells the player if it can affect that target. I know,i think i read in some tweet that that's not really how it works, but unless the change creates problem, i think i'll stick with the "caster belief" concept. If the character (not the player) has reason to believe that the spell would work, let him try, as long as it does not end up in abuse.