Project Arcana: Illusion Makes My Brain Hurt 1

Wile E. Coyote, Super Illusionist

Let me start by restating that 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.

So, let’s see how 5e describes the School of Illusion:

Illusion spells deceive the sense or minds of others. They cause people to see things that are not there, to miss things that are there, to hear phantom noises, or to remember things that never happened. Some illusions create phantom images that any creature can see, but the most insidious illusions plant an image directly in the mind of a creature.

Okay, let’s break this down Barney-style.

Illusion spells deceive the [senses] or minds of others. …

A good start. Illusion deceives the mind or senses. This works because to the mind, senses are just an information feed. If we affect that feed, we can effect mind (or whatever in the creature reacts to that sense organ).

…They cause people to see things that are not there, to miss things that are there, to hear phantom noises, or to remember things that never happened. …

Damnit 5e! We had such a good start and you biffed it already.

If illusions are affecting the mind or sense pathways directly, it makes perfect sense that the creature is seeing (sensing) things that are not there. They aren’t; they’re figments in his mind, or generated in the nerve pathways of his senses. This ties to the first sentence perfectly. And if you can have phantom images, you can have phantom noises.

But what the hell with “…remember things that never happened.”? Umm… No. Absolutely not! The creature is remembering something that – as far as it is concerned – did happen. (“Hey, remember the time we saw the Giant Purple Snorklewacker?”) There are no Illusion spells that create false memories, they are real memories of false events. Plus, the 5th-level Enchantment spell Modify Memory does exactly this.

Let’s go back to the first sentence briefly: illusions deceive. This is the critical concept, because if an illusion is made of some ‘stuff’ or makes actual noise or has an actual odor, it is not deceiving the senses. The sense is working just fine, thank you. If Illusory magic is deceiving the senses, then it must be working on the nerve channels that carry the senses, rather than changing what enters the eyes, ears, or nose.

And so we limp into the last sentence with a heavy heart and a sense of dread…

Some illusions create phantom images that any creature can see, but the most insidious illusions plant an image directly in the mind of a creature.

Wait, what? ‘…that any creature can see…‘? Isn’t the point of illusion that any creature can ‘see’ (sense) the illusion? But we know from the first sentence of the description that illusions happen in the mind of the creature, and then it says exactly that again at the end. Are you teasing me 5e, or are you doubling-down? Perhaps this is meant to draw a distinction between what happens ‘in the mind’ and what happens ‘in the senses’. I guess it’s easier to fool the senses? Sure, let’s go with that.

The interesting thing about all this is that since Illusion spells affect the mind, they’re close cousins to Enchantment spells:

Enchantment spells affect the minds of others, influencing or controlling their behavior. Such spells can make enemies see the caster as a friend, force creatures to take a course of action, or even control another creature like a puppet.

Where Enchantment is more direct, Illusion is kind of roundabout. One way to get a creature to do something is to try to influence its behavior by showing it something; but if you can simply force the behavior, so much the better.

Interestingly, lower level Illusion spells manipulate vision and hearing, and higher level spells add smell. The sense of touch is never really manipulated in an illusory manner. Mirage Arcane and Creation manipulate touch, but they’re way outside the description of this school. So, let’s deal with them later and just say for now that only vision, hearing, and smell are affected by this magic, although there doesn’t seem to be an obvious reason why touch should be left out.

There goes the neighborhood.

So, here is Project Arcana’s enumeration of the School of Illusion:

Illusion spells deceive the mind or senses of others. They cause creatures to see, hear, and smell things that are not real, or to overlook those that are real.

This brings up interesting questions, like how does invisibility work? Since being invisible means that you can see things through the invisible object, one of three things is happening here:

  1. The creature is truly invisible and light passes through them.
  2. The creature is in some sort of pocket universe, and light bends around them.
  3. The creature is fully visible, but the mind of the victim is manufacturing what is behind the creature.

In the first method, the physical properties of the creature are being changed; that’s a textbook Transmutation. The second is moving the creature to another place, so it’s a Conjuration. The only method that makes a daggone bit of sense as an Illusion is the third. There have been many studies on both the mechanics of vision and the brain that show that this is exactly how our visual system works: It fills in information where it can or must.

In fact, this quirk of our brains perfectly supports the initial statement on illusion: that it is created in the mind. Our brains are wired so that with the merest suggestion, we can fill in all sorts of details. The Rorschach test – where people impose images on ink blotches – and our tendency to see faces in everything are proof of that.

An obvious question becomes: If the Illusion is being stuffed directly into your optic nerve, can it be seen in total darkness, or when you have your eyes closed, or if you’re blindfolded? The short answer is: no. If your eyes are closed or otherwise covered, then visual illusions don’t affect you because your brain is ignoring the unexpected input from your eyes. It’s like an enhanced disbelief. This would extend to noises to those wearing earmuffs and smells for those wearing clothespins.

If illusions happen in the mind, what does this say about truesight, which defeats many illusions out of hand? Truesight works just fine with this refocusing of Illusory magic. If Illusory magic affects the optic nerves and visual cortex, truesight resists those effects. Truesight is like a shielded signal cable carrying an encrypted signal; it can’t be hacked or manipulated.

And, because Matthew wanted everyone to know we don’t just vomit this onto a post, here’s a bit of our long discussion about the ramifications of a ‘mind only’ take on Illusion:

Matthew So, in your idea of Illusion magic, let’s say I Color Spray you, which blinds you. Would you then be immune to Hypnotic Pattern?


Shawn Yes, after being Color Sprayed you would be immune to Hypnotic Pattern. Here’s why: Color Spray overloads the visual cortex by overstimulating the optic nerves. This overloading prevents Hypnotic Pattern from registering on the optic nerve and visual cortex. Think of it like a picture that’s been overprinted by a pattern of white noise.

I do wonder, though: Why is the sense of touch left out? It’s not like illusions strictly deal with visual fakery; some of them have sounds and smells. I know it’s an early convention, because, y’know, it’s an illusion, which like, means your eyes? But it doesn’t take a lot of thought to realize that the skin is just as much a sense organ as the eyes, ears, and nose; and therefore just as open to influence. Major Image can produce hot and cold, but that’s a far cry from the detail that can be put into visual, auditory, or olfactory illusions, which can seem like anything.

Let’s leave touch alone for the time being, with an understanding of “Yeah, why not?”

I’ve just worked hard to show that illusion is a magic that directly affects the mind instead of affecting the environment. In the next installment of Project Arcana’s investigation of Illusion, I’m going to be an analyzing Illusions spells to see which can possible conform to that basic mechanic.

SPOILER: Some of them are definitely going bye-bye.

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