# Can you create an illusion of empty space?

I've been thinking of various ways for a crafty Illusionist/Rogue to 'hide in plain sight' by essentially creating the cover that they want to hide behind.

Ideas include things like:

• Create a wall that is 2.5ft closer than it really is and hide in said space
• Create some innocuous barrier or container and hide within it
• Create a 'sheet' that essentially has what an empty room looks like 'painted' on it, so someone walking past an open door would see an empty room.

From different discussions I've had, these all should work, but the one lingering one I have is, what if my illusion is simply 'empty space'?

If I were to create an illusion of empty space and then place myself in it, would I be essentially invisible?

What if I created an illusion that was partially-empty space, like a 5x5 cube of swiss cheese? Would it seem like there was a swiss cheese cube formed around my person or could my 'fake-empty-space-image' fill the holes?

Would my 'empty space' illusion simply need to work like the aforementioned 'sheet of what I expect you to see' in order to function (and thus most likely only work from limited viewing angles)?

• How is your "empty space" concept different from invisibility? Apart from the fact that it is much easier to create if possible. Commented Jul 31, 2017 at 13:51
• @Szega To name a few, it's immobile and breakable with an investigation check or simply passing through the space with your face. Commented Jul 31, 2017 at 13:52
• Somewhat related: rpg.stackexchange.com/questions/97501/… Commented Jul 31, 2017 at 13:55
• What spell do you mean? Commented Jul 31, 2017 at 13:58
• I think there's probably some distant relationship between the above question and this question. Second cousins, maybe? Commented Jul 31, 2017 at 15:47

It is not possible with minor illusion, as with that

You create a sound or an image of an object (PHB 260)

and neither vacuum, nor air is usually considered an object. (There are discussions about this, looking them up is left to the reader.)

Nor could you use mirage arcane, as that explicitly states, that

The spell doesn't disguise, conceal, or add creatures. (PHB 260)

With silent image and major image there is a hint of possibility:

You create the image of an object, a creature, or some other visible phenomenon (PHB 276, 258)

It comes down to whether that the space inside the illusion is filled with air is a phenomenon. Even if we accept that it is, this illusion has to change relative to the viewer, which would require precise calculations from the caster and would be essentially impossible against more than one observer.

My personal ruling would be that this is an abuse of the spell and not allowed. It is much more streamlined and easier to handle this way. If a PC wants to be invisible, there is already a spell for it and not even that high level.

• Nice answer. And yeah, air is not a visible phenomenon. Commented Jul 31, 2017 at 14:38
• "which would require precise calculations from the caster" which of course the magic takes care of for you Commented Jul 31, 2017 at 21:05
• @Szega it's an illusion - it's not much good if it can't "Illude" people. The "image" of an object must look like the object under different lighting conditions and different points of view otherwise it is not the image of the object. Commented Jul 31, 2017 at 23:45
• @Szega sorry, what's a "photon"? - creatures see by means of magical rays that shoot out from their eyes Commented Aug 1, 2017 at 8:55
• We can cut this short: Does the spell description state, that there are limitations in regard to multiple perspectives/angles/distances/etc? If no, then there are no such limitations. End of story. I have seen this play out dozens of times and it never works. Someone claims that THIS single, randomly chosen "problem" must be considered for the magic, because... well, because the person bringing this up thinks it's important. It never is. It's magic. It's work as described. You are free to design an optics-compatible illusion magic system if you want that kind of thing. But this isn't it. Commented Aug 1, 2017 at 10:00

Of course you can, just not a very good one. Since you're limited to illusory "objects," it's going to be, like you suggested, pretty much the same as your "sheet with a [photorealistic] picture of an empty room" only you've got one sheet on each side of an illusory cube.

Such an illusion would be roughly comparable to things like the chalk artists who draw pictures of holes and other impressive things on the sidewalk. Extremely believable when viewed from the intended angle, but stepping too far to one side or another results in the parallax giving it away almost immediately. If using a spell that allows the illusion to be altered on an ongoing basis you might be able to track a person or small group and adjust it to continuously be what they expect to see, but it's not going to be an easy thing to do and will become close to impossible if they split up.

How successful this would be as a tactic will be highly dependent on placement. Near a wall would work OK as the parallax will be minimized. And the further away from the observer the harder it will be to spot. In a room with say polished obsidian walls and floors where there aren't any distinguishing characteristics for the eye to use to see the parallax it might even hold up to anything short of someone walking into it.

Do note two things though:

First, if I were the DM, I'd probably ask for a perception (or maybe stealth, I'd have to think about it) check to determine how clearly you can visualize exactly what texture needs to be on the cube to make it appear empty from a particular location. (Though I'd give you a big bonus if you took the time to scout it out and actually look at it from that location.) This isn't a normal "hey, there's a barrel here" use of an illusion spell, this illusion has to merge flawlessly with its environment, even moreso than putting an illusory wall over a doorway. If you don't line the bricks up with the background, or if you cut off half a wall sconce, it just got a lot more likely that somebody will notice. They won't be able to see through it until they realise it's illusory, but "Hey Thak! There's a weird piece of wall standing in the middle of the room!" is generally not something you'll be pleased to hear.

Second, consider whether you actually want your DM to think of doing this. This is the kind of trick that gives a much larger advantage to well-entrenched defenders than to wandering adventurers since the defenders will have had time to study and perfect the appearance of their illusion to match their intended purpose.

Other than that though, "Illusion of what this place would look like except without me in it as seen from over there" has been a staple part of more D&D campaigns than I can count. It gets past some of the weaknesses of Invisibility at the cost of being usable in a much more limited set of circumstances and being easier to pierce once the other guys realise what's going on.

• Not all Illusion spells are limited to objects. Commented Oct 5, 2019 at 22:44

## Probably not

RAW, there are no strict rules on what exactly illusions can or cannot be, so the standard answer is "ask your DM".

If you are the DM, consider two things:

• Spells only do what they say
• A spell doesn't do X if there is another spell of the same or higher level that does X

So the result depends on what spell is used. Let's take the Minor Illusion for example.

Rules as intended the Minor Illusion spell creates an illusion of a simple object (see the 2019 Sage Advice Compendium):

An illusory object made by minor illusion is meant to be like a stool or a rock

It cannot create an atmospheric effect like fog, or lighting effect like light or darkness, or visual effect like reflections or invisibility. There are other spells for such effects - Fog Cloud, Light, Darkness and Invisibility.

Keep in mind that, aside from Invisibility spells, no illusion spells can make a creature completely invisible, or make them look like a part of terrain. Even the high-level Mirage Arcane spell can't conceal creatures inside the illusion:

The spell doesn't disguise, conceal, or add creatures.

Instead, Illusion spells can change creature's appearance (Disguise Self, Seeming spells) or substitute their visible location (Mirror Image, Mislead).

Yes. There is an edge case example of a low-level illusion spell that can "create an illusion of empty space", although it can't be used to make you completely invisible I don't think.

The disguise self spell can make parts of "yourself—including your clothing, armor, weapons, and other belongings on your person" invisible. For example:

If you use this spell to appear thinner than you are, the hand of someone who reaches out to touch you would bump into you while it was seemingly still in midair.

Potential uses (open to some DM discussion) for a crafty Illusionist/Rogue might include things like:

• being able to hide your long boots that are sticking out under the curtain you are standing behind by disguising them as narrow hooves.
• lowering your height "1 foot shorter" so that your now invisible real head can peek in through a guards window but you remain out of sight below the sill.
• or maybe even making an object disappear by sticking it up your robes, and then casting disguise self to make yourself thinner again.