D&D 5E Magic Missile vs. Mirror Image

[Arial Black]

What's good for the caster is good for the martial. If the fighter can't tell who the caster is when he "targets" with an attack, a spell caster should similarly be unable to tell who the caster is when choosing a target for his magic missile or other spell. Mirror Image should apply equally to both martial and casters.

The spell already applies equally to both martials and casters.

Both martials and casters can target the real guy despite the images. In fact, neither is allowed to target the images directly. The only way for an image to be targetted is if the real guy is targetted by an attack roll then mirror image might re-direct the incoming attack onto an image.

The caster's attack rolls and the martial's attack rolls are equally affected by mirror image.

If the caster targets the MI guy with something that doesn't require an attack roll, MI has no effect.

If the MARTIAL targets the MI guy with something that doesn't require an attack roll, MI still has no effect,

The spell affects martials and casters in exactly the same way.

If you want to target a creature with anything, you just have to be able to see it. There is no 'roll to target' a creature. Simply choosing a target you can see is 100% effective.

If you need to make an attack roll, you 100% choose your target, but the attack roll may result in you missing your target.

But the choosing of the target is never a random process, even for those protected by mirror image. You target the creature 100%, as normal. Then if, and only if, an attack roll is required to hit your target, then MI may re-direct your attack onto an image.

This is how the game system works regarding targetting. You 100% target the thing you want to target as long as you can see it. This is true not only for spells without an attack roll but also for spells with an attack roll! It's just that those with attack rolls, athough targetted 100%, may miss that target.

 

[Maxperson]

The spell already applies equally to both martials and casters.

Both martials and casters can target the real guy despite the images. In fact, neither is allowed to target the images directly. The only way for an image to be targetted is if the real guy is targetted by an attack roll then mirror image might re-direct the incoming attack onto an image.

From the spell...

Three illusory duplicates of yourself appear in your space. Until the spell ends, the duplicates move with you and mimic your actions, shifting position so it’s impossible to track which image is real. You can use your action to dismiss the illusory duplicates. 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 clear that you can't tell who the real caster is and have to randomly get lucky to actually target him. You aren't actually targeting the caster unless the d20 roll says so.

If the caster targets the MI guy with something that doesn't require an attack roll, MI has no effect.

Because nonsense. From the above the caster should be randomly targeting images just like the martial PC. The caster can't tell which image is which since it's impossible for him to do so and would be targeting an image, which the spell explicitly says that you can do. The spell is very poorly worded and makes it seem like an attack is being re-directed, when it's actually just the attacker being unable to tell which image is you.

 

[Ristamar]

It's clear that you can't tell who the real caster is and have to randomly get lucky to actually target him. You aren't actually targeting the caster unless the d20 roll says so.

Thankfully, Magic Missile doesn't bother with a d20 since it's not an attack (in the D&D d20 roll-to-hit sense of the word).

I don't understand the false equivalency being peddled. Magic Missile isn't an attack. It doesn't require a spell attack roll. It can't miss (The fighter cries "Unfair!) It can't critically hit a target (The wizard responds, "Unfair!")

A martial bemoaning a targeting quirk of a caster's class feature (i.e. casting Magic Missile) seems about as relevant as a caster complaining that he doesn't get the martial's benefit of a Fighting Style even though the caster may be wielding the same weapon as the martial.

 

[guachi]

No, that's how Mearls ruled it. That makes it official, not correct. That's a consequence of "Rulings, not rules."

Personally, I recommend avoiding Mearls & Crawford's responses if at all possible. Seriously. Read through the Sage Advice columns and tweets. You'll find an alarming number of responses that make you say, "Wow, that's exactly the opposite of way I would rule," and more than a few that will make you say, "No, that's completely stupid. I have no interest in playing the game like that." Eventually you'll realize that it's not worth bothering with.

Exactly once have I seen Crawford tweet or write up a longer Sage Advice column that differed from my interpretation of the rules. That's because I find the rules, while not always obvious, have enough of a consistency that you can figure out what the meaning is. Often, that means looking in different locations or comparing and contrasting wording on different abilities or effects, but it can be done.

Too often, people are inferring things from abilities that the rules don't say.

 

[guachi]

But what if the target isn't a valid target? Eldritch blast, magic missile etc. can only target creatures, not objects or illusions! Does that mean that you can aim at a chest with one of these spells and if the spell fails to materialise then the spell is now a magic mimic-detector?

No. The spell is cast normally, but doesn't affect an invalid target.

If you cast eldritch blast at what may be a chest or may be a mimic, it's not that the the spell fails to materialise if it's a chest, it's that the beams don't affect a chest at all; the beams only affect creatures.

When you cast magic missile 3 (or more) missiles appear and then streak toward the target(s). If the target is invalid it doesn't mean that the missile never appeared in the first place or that it refuses to streak toward the target because the missile 'knows' that the target is not a creature. No, the missile streaks towards the target as normal, but has no effect if it is not a valid target.

I'm not certain this is explicitly stated anywhere, that casting a spell and having no valid targets means the spell (and potentially spell slot) is wasted. However, we have an analogous situation with holding an action (or whatever it's specifically called) where you use your reaction and name a trigger. If the trigger doesn't occur by the time your turn rolls around again, you expend the spell (and potentially spell slot).

I don't see how the situation you're describing and one where you hold your action are fundamentally different in "how to cast a spell and have it do nothing".

 

[Maxperson]

Thankfully, Magic Missile doesn't bother with a d20 since it's not an attack (in the D&D d20 roll-to-hit sense of the word).

It does bother with a d20, just like I quoted. Read the spell.

I don't understand the false equivalency being peddled. Magic Missile isn't an attack. It doesn't require a spell attack roll. It can't miss (The fighter cries "Unfair!) It can't critically hit a target (The wizard responds, "Unfair!")

There is no False Equivalency going on here. I'm not claiming it's an attack in the same sense as swinging a sword. I'm showing you that it's impossible to know which image is the real one, so the only way to determine who a caster SHOULD be able to target is with the same d20 roll that martial characters are limited to. The caster isn't able to determine who the proper target is any better than the fighter. That's a right and proper equivalence.

A martial bemoaning a targeting quirk of a caster's class feature (i.e. casting Magic Missile) seems about as relevant as a caster complaining that he doesn't get the martial's benefit of a Fighting Style even though the caster may be wielding the same weapon as the martial.

Probably a good thing I'm arguing reason then, and not complaining about one vs. the other.

 

[Ristamar]

So I assume you allow AoE effects to hit and destroy all the images since they would all be valid targets?

 

[Maxperson]

So I assume you allow AoE effects to hit and destroy all the images since they would all be valid targets?

Yep. That's what I would rule for sure. Unless the AOE required an attack roll, then it might miss some images.

 

[Arial Black]

From the spell...It's clear that you can't tell who the real caster is and have to randomly get lucky to actually target him. You aren't actually targeting the caster unless the d20 roll says so.

Not according to the spell:-

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.

At no point does the attacker choose to target an image. The attacker targets the creature, and does so 100% successfully.

'Targetting' something, and 'rolling to attack' something, are different things. There is no 'roll to target'. You don't have to roll to see if you successfully target a creature, either with weapons or spells with attack rolls (like flame bolt) or spells without attack rolls (like hold person). You successfully 'target' the creature you want (that you can see within range) 100% of the time.

Whether or not the attack affects the (100% successfully targetted) creature is a different thing. There might be an attack roll (which may hit or miss), there may be a saving through, or it may automatically affect the target (like magic missile).

From the above the caster should be randomly targeting images just like the martial PC.

From the above, the attacker targets the creature, not any of the images. The spell itself is the only thing that can switch the target to an image; the attacker cannot do so.

The caster can't tell which image is which since it's impossible for him to do so...

Fortunately, he doesn't need to know which image is real. They are all images of the one creature (even the real one) and all that is required to target the creature is that you can see the creature.

...and would be targeting an image, which the spell explicitly says that you can do.

The spell certainly says that the attacker targets the protected 'creature'. There is no way in the spell description for the attacker to target an image, only the workings of the spell itself can do that.

The spell is very poorly worded and makes it seem like an attack is being re-directed, when it's actually just the attacker being unable to tell which image is you.

It's worded just fine for the correct interpretation. You're only dissatisfied with the wording because it results in something you don't want. The spell seems to be saying that the attack is being re-directed simply because it is being re-directed!

Conceptually, when you have to accurately aim an attack in order to hit your chosen target (i.e. an attack roll is required) then the swirling images are a problem. But they are no problem at all if all you need is to choose a creature you can see and no accurate aiming is required, like hold person or magic missile. You just have to fart in it's general direction and you will target the creature you want with 100% certainty. Whether you affect the target is another matter, usually (but not always, c.f. magic missile) involving an attack roll or saving throw.

 

[Arial Black]

Yep. That's what I would rule for sure. Unless the AOE required an attack roll, then it might miss some images.

So you would rule that a fireball destroys the images!

A duplicate can be destroyed only by an attack that hits it. It ignores all other damage and effects

All this time we thought you were arguing about the magic missile spell described in the 5E PHB! It's now clear that you are talking about the version you made up in your head!

You've wasted our time. We were talking about the actual rules, not your home-brew.