D&D’s illusory magic is an odd, half-baked duck, and it never quite makes sense.
Now, I favor the idea that illusory magic affects the mind, acting directly on the nerve pathways from sensory organs to the brain (or whatever reacts to the sensory input in the creature). In my opinion, there is no other reasonable and internally consistent interpretation of this particular flavor of magic. Interestingly, this makes illusions closely related to enchantment magic, which also directly affects the brain.
Another theory is that an illusion is a magical hologram, and that it can be seen because it reflects visible light the same way a solid object does. This would make it akin to the holodeck on Star Trek, where laser holograms are combined with force field effects to make interactive objects. Let’s leave aside that the holodeck is the most stupidest idea ever, because how do you go swimming – and get wet – in a hologram and force field? This happened in the film ‘Generations’. And don’t even start thinking about Riker and his jazz-loving holodeck girlfriend, Domino. That will just creep you out. At least, it should creep you out.
A third concept is that the illusion materially exists in some fashion. This is clearly not correct most of the time. Illusions may trick the viewer into behaving as if they are there, but they can’t be touched. An example is Hallucinatory Forest: adventurers will work to skirt the trees, but if they close their eyes or disbelieve they can simply walk through them.
So, let’s talk about Mirage Arcane, which may be the most powerful – and singularly ridiculous – spell in D&D.
You make terrain in an area up to 1 mile square look, sound, smell, and even feel like some other sort of terrain.
The terrain’s general shape remains the same, however. Open fields or a road could be made to resemble a swamp, hill, crevasse, or some other difficult or impassable terrain. A pond can be made to seem like a grassy meadow, a precipice like a gentle slope, or a rock-strewn gully like a wide and smooth road.
Similarly, you can alter the appearance of structures, or add them where none are present. The spell doesn’t disguise, conceal, or add creatures.
The illusion includes audible, visual, tactile, and olfactory elements, so it can turn clear ground into difficult terrain (or vice versa) or otherwise impede movement through the area. Any piece of the illusory terrain (such as a rock or stick) that is removed from the spell’s area disappears immediately.
Creatures with truesight can see through the illusion to the terrain’s true form however, all other elements of the illusion remain, so while the creature is aware of the illusion’s presence, the creature can still physically interact with the illusion.
Here we have a spell that creates a huge ‘illusion’ that, for all intents and purposes, actually exists and with which players must interact. If they have truesight the interaction is surprisingly voluntary: “…the creature can still physically interact with the illusion.” (Emphasis mine. ).
The existing terrain can be altered in significant ways, keeping within the general contours of the land: ‘…it can turn clear ground into difficult terrain (or vice versa) or otherwise impede movement’. The spell can also facilitate movement, since it states that ‘…a rock-strewn gully [can be made to seem like] a wide and smooth road’. It also plainly states that a precipice can be smoothed into a gentle slope, or a crevasse introduced into flat terrain. So, there is wide variation available, so long as the new terrain matches the shape of the land at the edges of the illusion.
Some of the wording (‘…made to resemble…‘, ‘…seem like…’) would indicate that Mirage Arcane is just an illusion to which you are reacting but is not really there. That may be true of lower-level illusions, but it is absolutely not the case with Mirage Arcane. This is because you can also create structures with Mirage Arcane, and when asked about these structures, Jeremy Crawford specifically said in his ‘Sage Advice’ Twitter feed:
“You can climb an illusory tree formed by mirage arcane.”
And if you can climb an illusory tree, then you can climb the ladder of an illusory tower, walk on the slope of an illusory hill, be impeded by illusory rocks, or have your path smoothed by an illusory road.
So we know these things:
- Mirage arcane can create illusory terrain, flora, and structures.
- The illusory terrain can deviate wildly from the true terrain.
- Creatures without truesight must interact with the illusion. Creatures with truesight can interact with the illusion.
- Interaction with the illusion works as if the illusion is real, demonstrated by the confirmed ability to climb trees.
A quick look at lower-level illusion spells like Hallucinatory Terrain shows that attempts to touch do not result in contact. This supports the idea that an illusion is either a ‘hologram’ or created directly in the mind of the victim. It is important that Mirage Arcane says that even those with truesight ‘…can physically interact with the illusion’. This statement backs up other statements in the description and makes it clear that there is a physical solidity to the illusion.
Clearly, Mirage Arcane is something more than just an illusion!
And physical interactions with Mirage Arcane change the relationship to the world. If I can climb a tree, I can see further. I can fall and get hurt. If I can fall, then adding a crevasse will have dire results. But, I can also not fall! The description states that I can turn a sheer cliff into a gentle slope, I can stroll instead of falling.
This raises obvious questions: If I create an illusion that contains food – say, a field of corn – can I eat that corn? If I can climb a tree, I ought to be able to eat an ear of corn. And if I can eat that ear of corn, can I digest it? Do the nutrients become component parts of my body? If they do, what happens after the spell ends, or I leave the area of effect? Is the food stripped from me, and I’m now starving?
So maybe I can’t make corn. But I can make trees! What if I made an apple tree? Can I eat the apples? What if I had a pet beaver? Can he eat the trees?
The description says I can make rocks, and a hill. So I have the components I need to make a landslide.
This spell would also replace a brigade of combat engineers. Need a river bridged? No problem! Need a wall breached? This thing can replace a good wall with a knocked down wall, or make a tunnel through the wall. Assaulting a castle? This spell creates structures! Create a higher wall around the existing keep and throw rocks down on their heads! Need a village or town wiped out? Create a hill across a river valley upstream for a few days and then let nature take its course.
But even better, this is a good example of a spell that could clearly be put to more profitable use by any magic user with half a brain.
Allow me to reference Disney’s beautiful and silly Treasure Planet. Treasure Planet was, of course, Treasure Island‘ adapted to a space setting. The ships were classic sailing-era vessels that sailed the aether between worlds. The crux of the entire movie was the search for the treasure of the legendary pirate Captain Flint, who had the ability to appear from nowhere, raid passing ships, and disappear to hide the loot on the mysterious “Treasure Planet”. The upshot was that Captain Flint controlled a device that allowed him to transport between any two points in the galaxy instantly, instead of taking days, weeks, or months sailing. He used this ability to rob ships, make himself an outlaw, and die alone in the midst of the horde of stuff he’d collected.
Imagine how much happier – and richer – Flint would have been if he’d not been an idiot and, instead of using this device to raid ships, had started the ‘Treasure Planet’ version of Federal Express!
The same here: If I’m a magic user who can throw Mirage Arcane, I’m going to use it to make piles of money. Remember that the spell allows for a square mile of illusory terrain that follows the contours of the land at the edges, can have structures, and can be interacted with. I’m going to find the widest river, deepest ravine, narrowest harbor mouth or highest ridge line, create a bridge or tunnel, charge a few coins a head as toll, and retire. Except for recasting the spell once every ten days, I can spend the rest of my time swimming in my money bin.
Here’s the kicker: I can make a square mile of terrain. If I create a road 12 feet wide, this spell allows me to make it 440 miles long! That’s the road distance from Boston to Washington D.C.!
Money bin? Hell, I’d have a money arena!
Okay, okay. The spell states ‘…in an area up to one mile square…’. One interpretation (the fun one) is that the area is a square mile, but I suspect the intent was the illusion had to be within a square area up to a mile on a side. Now, that does limit my ability to establish the Boston Post Road, but I can sure build a hell of a bridge! The George Washington Bridge is only 4,700 feet long. The Golden Gate Bridge has lengthy approaches, but spans less than a mile of open water.
Frankly, the possibilities are limitless and fantastically unbalancing. The spell needs to be completely rewritten to reflect the fact that the illusory terrain is, in fact, illusory.
Having to guess, I think that the intent of this spell was to allow a wizard to create an illusory keep or home that was in all respects quite real as long as the wizard maintained the spell. This is also probably why Mirage Arcane has an astounding 10 day duration! My recommendation to WotC is to split Mirage Arcane into two spells: a souped-up version of Hallucinatory Terrain, perhaps more convincing, but no more real, and an enhanced version of Mordekainen’s Magnificent Mansion, which would include grounds and be more enduring.
And that’s all I’m going to say about Mirage Arcane. But D&D’s magic system is rife with inconsistencies and poorly thought-though implications. I’ll be talking a lot more about it in future installments.
Okay, one more thing about Mirage Arcane: A final sure-fire money-maker!