Inspired by What happens if I try to grapple an illusory duplicate from the Mirror Image spell?, what happens if I successfully grapple the wizard, rather than targeting one of the duplicates? Is the wizard's spell negated because I'm grappling him?

Mirror image states:

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.

The illusory duplicates are of yourself, not others, so couldn't my allies just target the one I'm holding?

No

The mirror image rules still apply because the spell is still active. The 'fluff' or narrative of description of why is up to the DM.

The only ways to bypass are if you aren't making an attack roll or if it is dispelled /suppressed.

Narrative example

To help give some substance to this, a possible description I would use is:

You're holding him with one hand, but his images are moving so quickly around it that even though you've got one hand on him, you really don't know where he is. Magic, man, it's wacky.

Table Reasons not to allow it

I'd also heavily consider what it would mean to allow grappling to negate the spell effect. If it's a player casting it, they've just used up a 2nd level slot to do so (which could be very impactful depending on the level of the caster). It's less of an issue for later, but resources are resources.

It also starts to open up potential other issues for why do some things work against it and others not.

Letting the spell do its job is both within the rules and makes good sense.

I am sure that others will disagree, but here is how I have always interpreted it and the logic for my decision. I have never had a complaint from any players when this explanation is provided. It involves inferring several factors that are not explicitly stated in RAW but so far as I know it complies with RAW and provides a logically consistent experience within the story.

Assumptions about mirror image:

1. The duplicates of the caster are not naked. The images include all clothes, armor, weapons, items, etc. that can are visible on the caster. It will also include any "visual effects" that exist at time of casting. If the caster's hair is on fire when the spell is cast then all of the duplicates will have burning hair. I even extend it to the ground immediately around them. If there is dust or powder on the ground getting kicked up by the casters feet as they move then all of the images will seem to be kicking up dust. Anything "attached" to the caster and visible to the players is duplicated and is visible on the duplicates. Anything else means that there is a difference between the images that could be used to identify which are fake.




2. The duplicates are constantly updated to always be identical to the caster as defined in assumption #1 so the spell effect of making them impossible to tell apart is maintained for the duration of the spell.

Mechanical implications:

• If the caster is knocked to the ground by a fireball then all of the copies fall to the ground.




• If the caster's clothes get charred by a fire then the clothes on all of the duplicates appear charred.




• If the caster's clothes are ignited by the fireball or other effect then all of the duplicate's clothes appear to be burning and smoking too.




• If the caster is slashed with a sword and starts to bleed then all of the images will appear to have the same wound.




• If the caster is hit by an arrow then all of the images will appear to have the same arrow stuck in them. The arrow is "attached" and therefore gets duplicated. If the caster pulls the arrow out and throws it on the ground then it is no longer attached and only one discarded arrow will be seen.

So far I think the implications will be agreed on by everybody. The next ones are more likely to be contentious.

• If a large net is dropped over the area of the caster, the actual net falls over the caster but simply passes through the duplicates. The duplicates are not dispelled because letting a net fall over a fixed location does not have an attack roll. It just falls through the illusory copies and lands on the ground. But given the above assumptions, the net is now "attached" to the caster just like their clothes and just just like an arrow that hits them during the fight. That means that every duplicate also has its own net. If there are 2 duplicates then it will appear that there are 3 nets overlapped and moving all around and there is still no way to identify the real caster from the duplicates. This also means that nobody will know which of the nets is real so the caster's allies will have problems trying to cut him out of the net. If the caster gets free of the net then the net is no longer duplicated and you only see one net on the ground.

Finally we get to the subject of this question. What happens on a grapple?

• If a character is successful in a grapple then they are "attached" to the caster just like the net or the arrow. The person who is holding onto the caster will also be duplicated and bystanders will still have no way of knowing which is the real thing. The caster's enemies will still not know which is the actual caster instead of a copy. The casters's allies will not know which of the grapplers is real and will have problems fighting the grappler off of the caster. Everybody will see multiple identical copies of the 2 people wrestling on the ground. If the caster is able to get free then the grappler is no longer attached and therefore no longer duplicated.

The spell is a visual illusion and says that it does not effect creatures that do not rely on sight. So long as the grapple is in effect, the grappler and the caster are touching each other and do not need to rely on sight for melee attacks against each other so these attacks will not be against a copy.

Based on my interpretation, a successful grapple negates the effects of the mirror image since it allows the grappler to use non-visual sense (touch) to know where the caster is located, but only for the creature who successfully grappled and only so long as they can keep their grip on the caster. Since my interpretation is that the grappler will also be duplicated, nobody else in the room knows which is the real image and which are the illusions so the spell is not negated for any of them.

Yes, it is valid to negate a spell's, such as Mirror Image, benefits by making it obvious what the result of the spell is.

Spells in D&D 5e do exactly what they say they do. There is no 'just flavor text' in 5th Edition. They do no less, but also no more than the words as described. This does not, however, mean that spells are always effective. Mirror Images provides some examples of how to overcome itself, both magically and mundanely.

Mechanically, Mirror Images does not provide a comprehensive list of caveats for methods that would identify you. I'm not saying it should be defeated by something like throwing a sack of flour over the spellcaster's square (the images likely conform to however you look at that moment); however, another creature being affected by the spell is far beyond its power and there is little other way to explain what a target sees when you successfully Grapple one of the images.

Notably, the description of Mirror Image's function is

it’s impossible to track which image is real.

You do not have to 'track' which image is real if you're simply attacking whatever your ally is holding. This is closer to "[relying] on senses other than sight" or "[perceiving the] illusions as false".

There are other instances of spells, especially illusion spells, being overcome and their effects no longer being effective (even if the spell is still active). While it is initially strange that the second paragraph of the spell is negated, that is the result.

Additionally, successfully grappling a target affected by Mirror Images deserves some form of reward, and being able to show your party "look, this is the Wizard" until they remove themselves from your grasp seems appropriate to me.