D&D 5E Magic Missile vs. Mirror Image

[Sorcerers Apprentice]

No luck needed, just creativity since a DM can always give a dragon spellcasting ability or magic items!

Any dragonborn PC can use this trick too if they or someone else in the party can cast invisibility

 

[pemerton]

Magic Missile is (probably) an attack. It lacks an attack roll though so it doesn't 'hit'.

'hitting' does require an attack roll.

Tthe word 'hit' implies an attack roll in 5E.

How so? Magic Missile says that "[e]ach
dart hits a creature of your choice" (Basic PDF, p 96) but does not involve an attack roll.

Was magic missile ever been an attack is D&D history?

Yes.

It is an attack in 4e.

It is an attack in AD&D (eg I've never encountered anyone who thinks that Magic Missile wouldn't break invisibility, which "remains in effect until it is magically broken or dispelled, or the magic-user or the other recipient cancels it or until he, she or it attacks any creature." (PHB p 70)

 

[pemerton]

You still cast a spell when using those magic items, so it will break invisibility. Invisibility doesn't refer to the type of action taken, but to casting a spell or making an attack.

Even suppose we go along with this - as opposed to deciding that, contra Crawford, using a spell from an item should be considered the "cast a spell" action (that was certainly the impression I just got from reading p 207 of the SRD) - what about the dragon?

Breath weapons trigger saving throws, they don't require attack rolls. And they're not spells. So does using a breath weapon not break invisibility? Or does it count as attacking even though not attack roll is involved and it's not called out as an attack?

I think it is an attack - at least for these purposes.

Which means that Magic Missile might be an attack for the purposes of Mirror Image.

 

[Leatherhead]

Any dragonborn PC can use this trick too if they or someone else in the party can cast invisibility

Now that is worth looking into. I wonder if it is an oversight due the frequency of other racial features being some form of spellcasting.

 

[Inglorin]

Is there (maybe?) an implied difference between "attack" (verb) and "attack" (noun) in the rules?

Mirror Image says: Each time a creature targets you with an attack (noun)...

Invisibility says: The spell ends for a target that attacks (verb)...

Attack (noun) has all the mentioned baggage. Needs an attack roll or be explicitly called an attack (like shove). While attacking (verb) doesn't. This could solve the invisible dragon conundrum. All for the cost of the terrible need to read the rules more closely than I am willing to do.

 

[Tony Vargas]

* since MM clearly is an 'attack' in language terms, there must be a reason why it does not count as an 'attack' in game mechanics terms

There's really not a strong (nor important) distinction in the style in which 5e is written, between 'language terms' and 'game mechanics terms.' Instead, there's this thing called a DM who rules on how things work in his game.

For those of us used to 3.x RAW or 4e jargon, it might well be very helpful to tease out something of the kind from 5e's natural language and use it to inform our rulings, but ultimately, that's what we're doing, making rulings for our own games, not defining into being jargon terms nor proving which interpretation is RAW.

Previous editions did not have 5E's definition of 'attack'.

4e made a distinction about 'attack roll' that was very similar, if, of course, more precise and and part of a whole spectrum of jargon. (It also eliminated the metagame distinction between an attack that was resolved by the attacker rolling a d20 and one that was resolved by the defender rolling, which was an unprecedented simplification.)

Yes, the very first incarnations of Magic Missile (OD&D and Holmes) essentially treated it as a magic arrow launched from a longbow. Even did 1d6+1 damage.

Thanks, I thought I recalled something like that

(And of course, pre-errata 4e also used attack rolls. It's amusing to me that in this instance, 4e is more closer to D&D's roots than anything else. )

(Wasn't the only similarity, either.) Even post-Essentials Magic Missile remained an 'arcane attack power,' but was changed from a hit line to an effect line, necessitating a cascade of errata.

 

[Lord Twig]

I didn't read this whole thread, but I have read quite a few similar threads. Personally I gave up on RAW in 5th edition quite a while ago. Which I think is actually the RAI.

By a strict reading Magic Missile can only target creatures. So you can't hit a door with it, for example. (And I swear this is going somewhere relevant to MM vs. MI. )

So, lets say you see a creature ahead of you in the darkness that is lying on the ground. Now he might be trying to hide, or he could just be dead and lying on the ground. So you cast Magic Missile at him. If he's alive the Magic Missile automatically hits, if he's dead he isn't a valid target for your spell and it fizzles.

Likewise if you target something you think is a creature, but turns out to be a scarecrow, or a dummy, you cast the spell, but it fizzles as the target is invalid.

Personally I rule that no matter what, when you cast Magic Missile, the magical bolts appear and fly at the target you have chosen. If the target is a living creature the magical energy tears into it and does damage. If it is not a living creature then the instant the missile touches the target it bursts into a harmless flash of light and the target is completely unharmed.

If you want to cast Magic Missile at a door? Go for it. It will hit the door and do absolutely nothing. However, if the door turns out to be a Mimic it will rip into it and do some damage.

So for Magic Missile vs. Mirror Image I rule that you choose all of the targets you want to hit. If you want to pick just one for all the missiles, roll to see if you got the right one. If you have 3 missiles and the target has 2 images, plus himself, it is easy. Both images and the target are each hit once. When a Magic Missile hits an image it fizzles as soon as it touches the image, but it also disrupts the image as it is now obvious that it is just an illusion.

If the number of missiles don't match the number of images then I have to reason out how to determine whether the actual target is hit or not, but this is pretty easy. For example, if you have 3 missiles and the target only has 1 image, then just roll like normal to see if the extra missile hits the target or the image. If you have 3 missiles and the target has 3 images then you have to roll a d20 for each missile. On a 6 or higher you hit an image. On a 5 or less you hit the target. Once you hit the target once he can't be hit again, so all other missiles hit, and destroy, an image.

So this is the ruling I have come up with based on the RAW. Some of it is obviously extrapolation, but I don't think any of it directly contradicts the RAW and it makes sense to me from an in-game perspective.

 

[Bacon Bits]

Not true. You still cast a spell when using those magic items, so it will break invisibility. Invisibility doesn't refer to the type of action taken, but to casting a spell or making an attack.

You didn't read the tweets:

Does using a magic item to cast a spell fall under the Use an Object action or Cast a Spell Action?

Neither. An action is one of those named actions only if it says it is.

Now, follow this logic. The first question is broad enough to cover scrolls, wands, staves, weapons, and even potions and wonderous items, etc. Nowhere do any of the magic item rules state what action using a given item is, just that you can spend an action to use them. So it must be in the item description, right? Yet all the magic items say is, "You can use this to cast a ~spellname~ spell." But given the context of this question, Crowford just said that a magic item has to say, "You can use this object to cast a spell by taking the Cast A Spell action." But nothing does that. Therefore, casting a spell from a magic item is never the Cast a Spell action.

 

[AaronOfBarbaria]

Therefore, casting a spell from a magic item is never the Cast a Spell action.

You missed the important part of what [MENTION=6854936]Sorcerers Apprentice[/MENTION] said.

It isn't that you break invisibility by using the Cast a Spell action - it is that you break invisibility by casting a spell, and while using a magic item doesn't necessitate the former (for some reason) it says right in the description of the item that it does involve the later when it says something like "you can use an action to read the scroll and cast its spell" (emphasis added).

 

[Sword of Spirit]

(All text in every 5e book (as well as the statement of one of the probably only two people who typed the actual text in the PHB, and that the other defers to as the rules guy) supports the principle that only things with attack rolls are attacks, so I'm not even going to join that part of the discussion.)

It seems clear to me that magic missile cannot dispel an image, since it has no effect on the mirror image spell.

Now, interpreting the remaining elements is difficult, but its difficult primarily because of certain effects only being able to target creatures.

I see there being two primary ways of looking at it.

Option 1 is the most by the book: You target the caster, and, barring shield, counterspell, or some such, all of your missiles hit the target interacting in no way with the images. All images remain--it is as if the mirror image spell just didn't exist for purposes of the magic missile casting.

But this means magic missile isn't totally targeted by sight, but also has a "seeking" function that allows it to know what a valid target is (ie, what is and is not a creature). (There are plenty of other spells, including ones that actually are attacks with this same problem (take ray of frost as an example)--they only target creatures, but not objects.) By the book, you can't even cast one of those spells on an object, because an object isn't a valid target. (It is unclear whether or not you simply can't cast the spell, or whether you cast the spell (and use the slot, if applicable) and it just fizzles.) So, as was mentioned, that makes these great illusion/creature detectors--which probably isn't intended. That is, however, the most by the book interpretation.

Option 2 requires a ruling that isn't by the book. You can rule that you can cast a "creature only" target spell at an object, the spell goes off, it does target and potentially hit the object, it simply doesn't have any effect on the object. So when you attempt to cast ray of frost at a rock, you shoot the ray, hit the rock, but the rock is unimpressed. Assuming this house rule, but taking everything else by the book, magic missile (and ray frost) should have the same chance of targeting the image as shooting an arrow would (ie, randomly roll for each missile to see which image it targets, and magic missile doesn't need an attack roll). In the case of magic missile, since it is not an attack, any missile that hits an image has no effect--the image is unimpressed. (In the case of a ray of frost it is unclear whether the image should be dispelled or not, since it is an attack and this option allows it to actually hit.)

This option only requires allowing "creature only" spells to actually target and hit objects, simply without (or perhaps with negligible) effect, otherwise it doesn't alter the rules of the game.

I had a heck of time trying to figure my answer to this question when I was running Lost Mine of Phandelver. I can't even remember exactly how I ruled it, and it quite possibly was neither of those options I just offered.

In my current preference, option 2 seems the more desirable, since it has no real downsides and the house rule improves other aspects of the game rather than messing them up. (In the case of ray of frost I'd probably rule that it doesn't dispel the image, since it only effects creatures.) Other options are possible, but they seem to be too fiddly or specific to mirror image whereas option 2 just makes a single rule/ruling for the whole game that can resolve this sort of ambiguity.