Illusions, lighting, and reflectance

Thyrwyn · Jan 10, 2019

FrogReaver said:
I’m saying that if an illusion behaves in a repeatable way that differs from a non-illusion then a player can quickly perform a test to reveal the difference.

Exactly. We are discussing a cantrip and a 1st level spell. They are limited by context and design to delay or distract.

He then knows it is an illusion despite the spell saying he doesn’t until he makes the investigation check.

I don’t read it that way - they are two separate mechanisms: 1) physical interaction (“I touch it.”), and; 2) spending an action observing it (“I look at it really closely”).

Henry · Jan 10, 2019

Ovinomancer said:
Illusions are super awesome and strong in my games. I'm not acting out of backladh for abused illusions. Instead, I following the descriptions as written. Illusions create an image of something, hence they add but do not subtract. They don't create or block light because they are images, mot physical, and the description does not say they do. They aren't mind affecting spells because they don't say they are -- the descriptions are clear as to what they do. When did reading the rules count as backlash?

I'm not clear from where you're getting the reasoning of "they add but don't subtract," because I'm missing it from the PH. Instead, it says Illusion spells "...deceive the senses or minds of others. They cause people to see things that are not there, to miss things that are there..." "miss things that are there" is pretty clearly "subtracting" to me. Even then, you seem to be taking the descriptions and extrapolating rules from them when they're in contradiction with the rules that are really there.

OK, in the case of minor illusion, "not create light" I get; "not create sounds alongside images" I get; but using the blanket "it's magic" catchphrase aside, it's part of the basic idea of blocking light and vision that are part and parcel of illusions. If it couldn't block light, even a little, you wouldn't see the illusion - it would be either a translucent or "invisible" illusion from its inception (both being useless).

To me, an illusion of a bridge would be like that camouflaged bridge from Indiana Jones and the Last Crusade, only in reverse - like a thick oil-canvas painted in midair, without the canvas, more substantial than a current-day hologram - because a current-day hologram is still very obviously translucent and a hologram, without even the slightest of Investigations. That's the only way to me to reconcile the language given in Minor and Major Image regarding its effects.

Past that, I don't have much more to contribute, because you have your lines drawn pretty strongly and so do I, and if your definitions of illusions work for your games, all good. I've come to mine because I've seen too many players in the past dismiss illusion magic because their DMs had very rigid and limited interpretations of what the magic allowed, to the extent that they were just happier blasting the problem as evokers because they knew that would at least work as described.

generic · Jan 10, 2019

Solution:

Illusions (like thick, coloured smoke), are effectively insubstantial for beings/objects passing through them, and are composed of coloured gases that have been trapped within insubstantial planes of extremely refined (and rather detailed) magical charge. They still block light, and cast shadows, but can't be consider substantial (as they are basically coloured gas and magical fields of directing electric charge.

FrogReaver · Jan 10, 2019

Ovinomancer said:
This, again. I have no idea what you mean by scientifically testable phenomenon. The illsuion does it's best to confirm to the environment to maximize it's effectiveness, so if there's a light source the illusion will have an apparent source for that light. Or, if the player insists, it will be easily recognizable that something is wrong.

That’s not how we run illusions. An illusionists illusions in our games don’t automatically add features to themselves to make them consistent with the environment. If that’s how you are playing them then I don’t have an issue with light passing through them since you’ve found a different way of avoiding the contradiction that i care about. But your method isn’t the only method to avoid that contradiction and the contradiction can be avoided without having illusions automatically add non referenced features to exactly match the environment.

Ovinomancer · Jan 11, 2019

Henry said:
I'm not clear from where you're getting the reasoning of "they add but don't subtract," because I'm missing it from the PH. Instead, it says Illusion spells "...deceive the senses or minds of others. They cause people to see things that are not there, to miss things that are there..." "miss things that are there" is pretty clearly "subtracting" to me. Even then, you seem to be taking the descriptions and extrapolating rules from them when they're in contradiction with the rules that are really there.

This is disingenuous, as the discussion is on the image spells. I've already been explicit that spells that remove things are specifically called out, like invisibility, which is in the illusion school. But, when discussing spells that can create objects that may or may not block light (depending on you argument), that's limited to a very specific set of spells that have uniform language about creating and image.

Here's minor image:
You create a sound or an image of an object within range that lasts for the duration.

Here's silent image:
You create the image of an object, a creature, or some other visible phenomenon that is no larger than a 15-foot cube.

Here's major image:
You create the image of an object, a creature, or some other visible phenomenon that is no larger than a 20-foot cube.

All of these have very clear language on what the spell does: they create an image.

OK, in the case of minor illusion, "not create light" I get; "not create sounds alongside images" I get; but using the blanket "it's magic" catchphrase aside, it's part of the basic idea of blocking light and vision that are part and parcel of illusions. If it couldn't block light, even a little, you wouldn't see the illusion - it would be either a translucent or "invisible" illusion from its inception (both being useless).

No, this is how real world object work with light. Illusions are magic, they do not follow physical laws and, in fact, break them to pieces. A hobgoblinish insistence that magic just does physics is weird. In order to block light, there must be a physical object which is not what the spell description says it does.

To me, an illusion of a bridge would be like that camouflaged bridge from Indiana Jones and the Last Crusade, only in reverse - like a thick oil-canvas painted in midair, without the canvas, more substantial than a current-day hologram - because a current-day hologram is still very obviously translucent and a hologram, without even the slightest of Investigations. That's the only way to me to reconcile the language given in Minor and Major Image regarding its effects.

That bridge from IJatC was an actual bridge. I don't see how an illusion is like a real thing, camouflaged or not. And there's nothing to reconcile in the descriptions of Minor and Major image -- the both create a visible image that has no physical existence.

Past that, I don't have much more to contribute, because you have your lines drawn pretty strongly and so do I, and if your definitions of illusions work for your games, all good. I've come to mine because I've seen too many players in the past dismiss illusion magic because their DMs had very rigid and limited interpretations of what the magic allowed, to the extent that they were just happier blasting the problem as evokers because they knew that would at least work as described.

And, again, I'm telling you that my interpretation is and has been very useful in game. Illusions do exactly what they say on the tin: they create an image, and possibly a sound. They don't block or create light, and they certainly don't require explanation in terms of science. Illusion magic in my games is very useful, provide you understand that what you can do is create an image and don't imagine you can darken rooms or make things disappear (conceal them under the image, sure). Read the actual descriptions and don't bring anything with you this time. Just do what it says and don't come up with reasons why it has to do other things. It's all right there in the descriptions.

Ovinomancer · Jan 11, 2019

FrogReaver said:
That’s not how we run illusions. An illusionists illusions in our games don’t automatically add features to themselves to make them consistent with the environment. If that’s how you are playing them then I don’t have an issue with light passing through them since you’ve found a different way of avoiding the contradiction that i care about. But your method isn’t the only method to avoid that contradiction and the contradiction can be avoided without having illusions automatically add non referenced features to exactly match the environment.

I see, there's been some misunderstanding. The illusion does it's best at the time of casting, or when an action is used to modify it. Illusions don't modify themselves on their own. But, that's a benefit -- a minor illusion covering a doorway will fail if a light source is ignited behind it if it was cast when the doorway was dark. I have no problem with a change to the environment rendering an illusion easier to detect -- it should be. We're discussing a cantrip or first level spell, here after all, not a super magical undetectable veil. If there's a light source already present when the illusion is cast, and the caster intends to cover it, the illusion will have an obvious source for that light -- in the case of a wall, it will have a torch or candles to mimic the source of light. If the caster doesn't intent that, because the light source will be moving away, it doesn't. The illusion will meet the caster's intent in the best way possible because I'm not out to screw over players for not describing their illusions sufficiently.

I suppose the difference here is that you believe an illusion should be able to not reveal itself if changes to environment occur. You don't want self-aware illusions, so you imagine them with physical properties like blocking and reflecting light as a real object would. Okay, but I disagree with the premise that a change in environment should never reveal an illusion. If you have a illusory wall with a torch behind it, that light comes through. If the torch goes out, it goes out. If a creature notices that change, it's a clue something is odd and may need to be investigated -- otherwise how would you ever find illusions absent touching everything (which is foolproof, but dangerous). A well purposed illusion is powerful even if it can be detected with sufficient change to the environment. What I dislike are illusion spells that double as tactical blinds -- hobbling enemies with arbitrary states of lighting that don't apply to the ambushing side, or being able to hide behind an illusion of a wall that you can see through. The latter is still part of the normal spell description, but that's why I have my one houserule illusions -- they don't fade on detection. But, I freely admit that's my preference. How illusions work, though, are right there in the spell descriptions.

Laurefindel · Jan 11, 2019

Dausuul said:
Please give an example of how this would happen. How would you "recreate" another spell using silent illusion? Keep in mind that silent illusion is automatically revealed by physical contact and can't move except when the caster uses an action to move it; an illusory blindfold over a creature's eyes would fail on multiple fronts (first because the creature is in contact with the blindfold, and second because the creature could take a single step and the blindfold would no longer be over its eyes).

I was mostly referring to copycat effect of light spells (if illusion can create light), invisibility effects (if illusion can remove/bend/reflect light), and darkness shenanigans (if illusion can block/absorb light). I'm not saying you advocated any of those, but that's why I think one should be careful about allowing illusions to create, block or reflect light.

But again, as Ovinomancer said, illusions as described in D&D (and fantasy in general) are irreconcilable with real-world physics. Something's got to give. In the face of this paradox, we've got to accept that illusions won't logically work or be rationally explainable, and go with the same willing suspension of disbelief that we are capable of for many other aspects of the game.

In order to be visible in the real-world, an object as to a) emit in the visible spectrum, or b) reflect the ambient light toward the onlooker (assuming there is ambient light in the first place).

Illusions are magical constructs that can make something visible and look real enough to fool anyone that doesn't physically interact with it, but that doesn't really exist. So far in this tread, it has been theorized that...

- Illusions don't create, absorb or reflect light in any logical ways: it just make the illusory item visible and indiscernible from a real one, because magic.

- Illusions block light and reflect it back to it onlooker (the reason we see them) but don't interact with the physical world in any ways, because magic.

- Illusions don't exist as a phenomenon but as a figment of the imagination of the onlooker. The illusionist therefore doesn't mess with our senses as mush as it messes with our mind. And this figment is the same for everyone, because magic.

Personally, I don't think one explanation is more valid than any other - all require that we ignore the laws of physics as we know them. However, I find that the first one is the simplest to explain and to implement within the RaW parameters of the spell without too much surprises and dubious shenanigans. And yet it remains a very powerful tool in the hand of a clever illusionist.

Imaculata · Jan 11, 2019

Ovinomancer said:
Again, I strongly disagree that illusions are able to remove things from reality. An illusory wall can't block light, so will instead have a feature that appears to emit the light.

As for illusory pits, well, they are illusions. If you jump into one, you get a surprise and some confusion as you appear to stand on empty air. Probably get advantage on the INT check. There's no mechanic that says you can't walk through an illusionary wall or stand where there's an illusion of a pit. Illusions are already powerful enough that they don't need strange mechanics like this. You just can't drop a silent image of a pit and have it foil all attenpts to cross it without a successful save. A badly placed illusion is like a badly placed fireball -- it doesn't work as well as you hope. If your opponent tosses a rope onto the illusory pit, it lies on the ground because the illusion can't make it disappear. You still got the round or two of delay, which is okay.

To me this depends on the level of the illusion spell. A minor illusion would be just that, an image of which the true nature is revealed when interacted with. But greater illusions may respond to interactions, and as long as the affected individual fails their disbelief-check, it may seem totally real. I do like your suggestion to have the illusion include a feature that emits light.

Ovinomancer · Jan 11, 2019

Imaculata said:
To me this depends on the level of the illusion spell. A minor illusion would be just that, an image of which the true nature is revealed when interacted with. But greater illusions may respond to interactions, and as long as the affected individual fails their disbelief-check, it may seem totally real. I do like your suggestion to have the illusion include a feature that emits light.

Within the scope of the spell, yes, but illusion spells have clear statements of what happens if interacted with. I can't think of any illusion spells that fit this except the explicit mind affecting ones (phantasmal x, weird) and mirage arcana, which is a weird illusion that creates tactile reality and can't be disbelieved at all.

And, to clarify, I said an apparent source for the light, not an actual source of light. "Emits" was a touch unclear above.

FrogReaver · Jan 11, 2019

Ovinomancer said:
I see, there's been some misunderstanding. The illusion does it's best at the time of casting, or when an action is used to modify it. Illusions don't modify themselves on their own. But, that's a benefit -- a minor illusion covering a doorway will fail if a light source is ignited behind it if it was cast when the doorway was dark. I have no problem with a change to the environment rendering an illusion easier to detect -- it should be. We're discussing a cantrip or first level spell, here after all, not a super magical undetectable veil. If there's a light source already present when the illusion is cast, and the caster intends to cover it, the illusion will have an obvious source for that light -- in the case of a wall, it will have a torch or candles to mimic the source of light. If the caster doesn't intent that, because the light source will be moving away, it doesn't. The illusion will meet the caster's intent in the best way possible because I'm not out to screw over players for not describing their illusions sufficiently.

I suppose the difference here is that you believe an illusion should be able to not reveal itself if changes to environment occur. You don't want self-aware illusions, so you imagine them with physical properties like blocking and reflecting light as a real object would. Okay, but I disagree with the premise that a change in environment should never reveal an illusion. If you have a illusory wall with a torch behind it, that light comes through. If the torch goes out, it goes out. If a creature notices that change, it's a clue something is odd and may need to be investigated -- otherwise how would you ever find illusions absent touching everything (which is foolproof, but dangerous). A well purposed illusion is powerful even if it can be detected with sufficient change to the environment. What I dislike are illusion spells that double as tactical blinds -- hobbling enemies with arbitrary states of lighting that don't apply to the ambushing side, or being able to hide behind an illusion of a wall that you can see through. The latter is still part of the normal spell description, but that's why I have my one houserule illusions -- they don't fade on detection. But, I freely admit that's my preference. How illusions work, though, are right there in the spell descriptions.

It seems to me that if changes in environment can reveal an illusion then you can disbelieve an illusion without taking an action and successfully completing an investigation check.

My reasoning is that if something other than an investigation check can reveal an illusion then the spell doesn’t work as written because there is now more than physical interaction and a successful investigation that can cause a character to disbelieve an illusion.

I think every illusion has something about it that can reveal it’s an illusion. I think that something isn’t consistent between illusions and that’s what the investigation check is for.