D&D 5E Magic Missile vs. Mirror Image

[KarinsDad]

You're correct when you say that "spells do what they say they do".

What magic missile says is:-



Therefore, images are not viable targets because images are not creatures.

Except that this "images are not creatures" interpretation would prevent a lot of spells from targeting Mirror Images. For example, Shocking Grasp. There are a lot of spells that only discuss targeting creatures within them which Mirror Image should protect against.

Magic Missiles "hits" creatures. A Mirror Image duplicate can be destroyed if it is hit. Therefore, Magic Missiles can hit different Mirror Images. I understand that the protection intent of Mirror Image is against attacks and spells that have attack rolls, but Magic Missile does not fall into the category of a spell that has a save either. It is an autohit and should be treated as such. It should autohit and Mirror Image should potentially protect against it.

Note: the only special aspect of this is that Magic Missile does state that it fires simultaneously which to me means that the caster has to pick targets ahead of time (i.e. the normal mechanics of Mirror Image should be avoided to handle this special case).

 

[Sword of Spirit]

Strange as it may seem, an illusion is not a valid target for magic missile. But it's not too strange, bearing in mind that a door, wooden chest, specific body part, fog, none of these are valid targets for MM either.

That doesn't mean that you cannot cast the spell at the illusion/door/chest/eye! What happens if you cast the spell at a non-valid target?



Each dart 'hits a creature'. Since spells do exactly what they say they do, then if you cast MM and target an invalid target, the spell does this:- "You create three glowing darts of magical force. Each dart fails to hit what you aimed at, because what you aimed at was not a valid target".

Against an invalid target the spell will still create three glowing darts, they will still streak towards your target, but will have no effect whatsoever.

This is a really good explanation of what should happen with a non-valid target. I think it should probably be interpreted similarly with most spells. Sure, you can designate an invalid target (otherwise things get weird) but if it isn't valid the spell doesn't affect it.

Against mirror image, since magic missile's autohit does imply more of a homing feature than an attack roll, I rule with Jeremy Crawford that it simply ignores the illusions and hits the caster--since they can see the caster and the spell is more of a blur kind of effect than anything (whereas it was a figment in 3e, 5e treats it more like a glamor). Still, I could see a case for creative usage of a player asking if they could intentionally try to pick out specific images (with a difficult Intelligence or Wisdom (Perception) check) and target the missiles at them. Of course, the missiles wouldn't do anything to images other than the caster, so it's a complete waste of time.

 

[Argyle King]

Strange as it may seem, an illusion is not a valid target for magic missile. But it's not too strange, bearing in mind that a door, wooden chest, specific body part, fog, none of these are valid targets for MM either.

That doesn't mean that you cannot cast the spell at the illusion/door/chest/eye! What happens if you cast the spell at a non-valid target?



Each dart 'hits a creature'. Since spells do exactly what they say they do, then if you cast MM and target an invalid target, the spell does this:- "You create three glowing darts of magical force. Each dart fails to hit what you aimed at, because what you aimed at was not a valid target".

Against an invalid target the spell will still create three glowing darts, they will still streak towards your target, but will have no effect whatsoever.

I see the point, but I still feel as though it leads to some weird situations.

For example, firing a magic missile at an object does nothing. But, firing a magic missile at an animated object does damage (or so I assume). Firing a magic missile at a chest also has different effects depends upon if the chest is actually a chest or a mimic.


I also feel like your interpretation that invalid targets can still be targeted still means there is some ambiguity because the mirror images of the caster would be invalid targets, which is what my original reasoning is based upon. Then again, how I see the spells working in my mind do not appear to match the programming language of D&D rules. In the end, what I believe doesn't matter because I'm not the person who wrote the rules.

 

[dco]

Except that this "images are not creatures" interpretation would prevent a lot of spells from targeting Mirror Images. For example, Shocking Grasp. There are a lot of spells that only discuss targeting creatures within them which Mirror Image should protect against.

You are right, most spells target creatures or objects, images don't fall in any of those categories. From the PHB Melf's acid arrow, Scorching ray and perhaps another one or two would be the only ones able to hit the images.
I'll continue doing it as always, you can hit images with magic missile and other spells.

 

[Arial Black]

Except that this "images are not creatures" interpretation...

'Interpretation'? Does anyone believe that an illusion is a creature?

...would prevent a lot of spells from targeting Mirror Images. For example, Shocking Grasp. There are a lot of spells that only discuss targeting creatures within them which Mirror Image should protect against.

The reason that shocking grasp can hit the images is not because they are valid targets (they are not) but because the spell description of mirror image says so.

Each time a creature targets you with an attack during the spell’s duration, roll a d20 to determine whether the attack instead targets one of your duplicates

It's not the caster of magic missile, shocking grasp or any other spell targets the images in and of themselves--those spells still target the creature--but that the magic of mirror image changes the target (possibly) to one of the images; a task otherwise not possible. MI makes it possible. Further, it only makes it possible if the effect is delivered by an attack roll. No attack roll, no mirror image messing with it.

Magic Missiles "hits" creatures. A Mirror Image duplicate can be destroyed if it is hit. Therefore, Magic Missiles can hit different Mirror Images.

Mirror image can only re-direct something that is an 'attack'. In 5E, this means 'attack roll'. MM doesn't use an attack roll, therefore is not an 'attack' that MI is capable of affecting.

I understand that the protection intent of Mirror Image is against attacks and spells that have attack rolls, but Magic Missile does not fall into the category of a spell that has a save either. It is an autohit and should be treated as such. It should autohit and Mirror Image should potentially protect against it.

The fact that MM doesn't have a saving throw does not turn it into an attack!

 

[KarinsDad]

It's not the caster of magic missile, shocking grasp or any other spell targets the images in and of themselves--those spells still target the creature--but that the magic of mirror image changes the target (possibly) to one of the images; a task otherwise not possible. MI makes it possible. Further, it only makes it possible if the effect is delivered by an attack roll. No attack roll, no mirror image messing with it.

Sorry, you cannot use the "it's not a creature" for one spell and not use it for all spells. That defense of your interpretation doesn't work.

Mirror image can only re-direct something that is an 'attack'. In 5E, this means 'attack roll'. MM doesn't use an attack roll, therefore is not an 'attack' that MI is capable of affecting.

There are a lot of different attacks in 5E that do not use an attack roll. Grapples, Fireballs. These are still attacks though and still use the Attack action. They are not attacks that use an attack roll. And yes, Mirror Image typically only stops those attacks that have attack rolls because its mechanic uses AC to determine whether a hit occurs.

Unfortunately, just like Mirror Image trumps the "creature" language of Shocking Grasp, Magic Missile trumps the "AC" language of Mirror Image.

Magic Missile explicitly states that it hits its target. Explicitly. Mirror Image loses an image if the image is targeted (controlled by the Mirror Image mechanics) by an attack that "hit" it.


This is a special corner case. Hence the reason people are discussing it. Both interpretations are totally valid. Yes, you have your preference, but there is nothing that indicates that your preference is the only valid interpretation. People wouldn't be discussing it for so many pages if it were crystal clear.

Magic Missile fits all of the criteria of Shocking Grasp (it has language about its target, it has language that it does a hit), the only difference is that it does not use the AC mechanics because it autohits.

As an additional note, Mirror Image does NOT state that someone has to make an attack roll to hit an image (as per your repeated claim). It gives the AC of the images so that spells that do use that mechanic can be adjudicated. An attack having to make an attack roll is your interpretation of what Mirror Image states. It does not explicitly state that, but since the majority of attacks that do hit require an attack roll, I can see where you interpreted it that way.

What Mirror Image explicitly states is: "A duplicate's AC equals 10 + your Dexterity modifier. If an attack hits a duplicate, the duplicate is destroyed. A duplicate can be destroyed only by an attack that hits it.". It doesn't state that an attack roll is required.

Magic Missile hits targets. Hence, it can hit duplicates.

In fact, Magic Missile is the ultimate (shy of Dispel Magic) anti-Mirror Image spell. Each missile can be targeted against a different image/creature and can destroy multiple images automatically.

 

[discosoc]

I'm amazed this is still being debated, considering Crawford cleared it up a year ago...

https://twitter.com/JeremyECrawford/status/709541359422582784

 

[discosoc]

It should autohit and Mirror Image should potentially protect against it.

Feel free to house-rule it that way, but it's not the way it works.

 

[Cognomen's Cassowary]

There are a lot of different attacks in 5E that do not use an attack roll. Grapples, Fireballs. These are still attacks though and still use the Attack action.

Grapples and shoves are expressly called out as special kinds of attacks which do not use attack rolls but are still made with the attack action. Fireball is not an attack, does not call for a spell attack in its description, and is not made with the attack action. Where are you even getting this?

I'm amazed this is still being debated, considering Crawford cleared it up a year ago...

https://twitter.com/JeremyECrawford/...41359422582784

Given that it's not ambiguous RAW, it was amazing that he even needed to clear it up.

 

[Argyle King]

Grapples and shoves are expressly called out as special kinds of attacks which do not use attack rolls but are still made with the attack action. Fireball is not an attack, does not call for a spell attack in its description, and is not made with the attack action. Where are you even getting this?



Given that it's not ambiguous RAW, it was amazing that he even needed to clear it up.

Not being ambiguous RAW is not necessarily the same as not being ambiguous. It's not unheard of for a rule clarification for an edition of D&D to go against what the letters on the page spell out.

In the context of 5e, while I'd agree that the RAW spell things out, there is also the issue of words not always meaning what words typical mean in the context of normal language. For example, check out the various threads concerning natural attacks, unarmed attacks, and attacks. The way the language of 5e is used to cover how those things interact with each other isn't exactly intuitive.