Illusions, lighting, and reflectance

[Thyrwyn]

From Minor Illusion: “Physical interaction with the image reveals it to be an illusion, because things can pass through it.” it also says you can create “an image of an object.”

It literally states that light (both philosophically and scientifically a “thing”) passes through it.

For those relying on physics to argue that it has to interact with light because it is an illusion of an object, and objects reflect light: it is an image of an object, and images do not reflect per se. holograms and projections do not reflect light.

If you allow the Minor Illusion to block light, it could be used to duplicate Darkness (2nd level) or Blindness (2nd level) just to name two.

There are several Illusion spells that fool the mind, and they are called out as such in the description. Neither Minor Illusion nor Silent Image have any such language. Spells like Phantasmal Force, which do fool the mind, are targeted (neither Minor Illusion nor Silent Image are), and allow a saving throw -before- taking effect.

 

[Dausuul]

From Minor Illusion: “Physical interaction with the image reveals it to be an illusion, because things can pass through it.” it also says you can create “an image of an object.”

It literally states that light (both philosophically and scientifically a “thing”) passes through it.

So... if a thing passes through the illusion, it is revealed. And light is a thing. Therefore illusions only work in total darkness.

Oh, air is also a thing. So illusions only work in total darkness, in a vacuum.

Gotcha.

If you allow the Minor Illusion to block light, it could be used to duplicate Darkness (2nd level) or Blindness (2nd level) just to name two.

If it can "duplicate" those spells, then a nonmagical cardboard box can duplicate those spells. Cardboard boxes: OMGBROKEN!

Come on. This line of argument is ridiculous. The ability, under certain limited circumstances, to extinguish a single light source is not remotely the same as creating a zone of magical darkness. It's like saying produce flame duplicates fireball because it can set stuff on fire.

 

[FrogReaver]

From Minor Illusion: “Physical interaction with the image reveals it to be an illusion, because things can pass through it.” it also says you can create “an image of an object.”

It literally states that light (both philosophically and scientifically a “thing”) passes through it.

For those relying on physics to argue that it has to interact with light because it is an illusion of an object, and objects reflect light: it is an image of an object, and images do not reflect per se. holograms and projections do not reflect light.

If you allow the Minor Illusion to block light, it could be used to duplicate Darkness (2nd level) or Blindness (2nd level) just to name two.

There are several Illusion spells that fool the mind, and they are called out as such in the description. Neither Minor Illusion nor Silent Image have any such language. Spells like Phantasmal Force, which do fool the mind, are targeted (neither Minor Illusion nor Silent Image are), and allow a saving throw -before- taking effect.

I find the physics argument interesting but not compelling. What I find compelling is that the spell requires a save to disbelieve. Providng consistent interactions with light gives any scientifically minded player a way to quickly test if something is an illusion without making a check. Since a check is required by the spell I can’t imagine illusions producing consistent scientifically observable effects. Thus an illusions interaction with light needs to be such that it’s not a consistent indicator that something is an illusion.

 

[Thyrwyn]

I find the physics argument interesting but not compelling. What I find compelling is that the spell requires a save to disbelieve. Providng consistent interactions with light gives any scientifically minded player a way to quickly test if something is an illusion without making a check. Since a check is required by the spell I can’t imagine illusions producing consistent scientifically observable effects. Thus an illusions interaction with light needs to be such that it’s not a consistent indicator that something is an illusion.

It doesn’t, though. The save is only required if one cannot interact with the image. “Physical interaction reveals the illusion, because things can pass through it.”

 

[FrogReaver]

It doesn’t, though. The save is only required if one cannot interact with the image. “Physical interaction reveals the illusion, because things can pass through it.”

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. He then knows it is an illusion despite the spell saying he doesn’t until he makes the investigation check. I find it necessary to avoid that contradiction and so my rulings will always maintain that the illusion is indistinguishable from a regular object unless the player succeeds on the investigation check or sees an object passing through the illusion.

 

[Ovinomancer]

I find the physics argument interesting but not compelling. What I find compelling is that the spell requires a save to disbelieve. Providng consistent interactions with light gives any scientifically minded player a way to quickly test if something is an illusion without making a check. Since a check is required by the spell I can’t imagine illusions producing consistent scientifically observable effects. Thus an illusions interaction with light needs to be such that it’s not a consistent indicator that something is an illusion.

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.

 

[Henry]

Come on. This line of argument is ridiculous. The ability, under certain limited circumstances, to extinguish a single light source is not remotely the same as creating a zone of magical darkness. It's like saying produce flame duplicates fireball because it can set stuff on fire.

A lot of the reasoning for extremely limited illusion school spells I first saw back in the AD&D days, when due to lack of clearly defined boundaries, illusions ran roughshod over DMs' games because players would argue all sorts of insane abilities for illusions. The backlash seems to be a reaction out of concern that illusions can duplicate other more powerful spells, but to me, unreasonably so. All of these things (duplicating darkness or blindness, etc.) don't stand up to scrutiny, (HA!) when just physically interacting with the illusion pretty much breaks it. For Minor Image, putting an "illusion cardboard box on someone" means they step five feet right and break it immediately. Putting an "illusory cardboard box on yourself" gives you 'heavily obscured" -- ONCE. It then clues them in that you are using illusion magic, and the jig is up anyway. It's a poor man's 5 foot obscuring mist that uses your action, and which one person can dispel immediately without so much as a spell.

Then, if we get into more powerful illusions, such as Major Image, people use these arguments to completely defang these spells, which leads to the same situations as back in AD&D -- no one wanting to focus on illusion magic, because it is a pale facsimile (irony intended) of other schools of magic.

What's next, because "things can pass through" a Major Image, then putting a red dragon Major Image in front of a bonfire reveals it to be an illusion, because "the light passes through it?" It's a third level spell, yet a Web spell would outshine it because it's more effective at stopping a few orcs? To me, people need to focus on the specifics given in the spell description's mechanics -- namely, in the case of Major Image, it looks, smells, and sounds REAL, until you either TOUCH it, or decide to try and pierce it with an Investigation check.

Those are what would make illusion magics usable, and to start nitpicking until the whole school is useless eliminates the point the spell is in there for in the first place. When I hear talk of "proper clever use of the spells" to me it seems to frequently mean "use of the spells in extremely limited circumstances that only I think will work, that I see fit to allow" rather than making inferences that actually flow from what the spell says are its capabilities.

 

[Ovinomancer]

Of course illusions affect things outside of their AOE. Illusions work on the minds of their targets; that much is obvious, since different people perceive the same illusion differently depending on whether they've made an Investigation check. And anyone fooled by an illusion is by definition outside of its AOE (if you're inside the AOE, you're physically interacting with it, so it doesn't work).

It's your inference that illusions are mind affecting, the rukes say absolutely nothing about this. Further, even if they are (for arguments sake) you are adding additional things past the description based on hiw you think mind affect illusions work. If you stick to the description, light is not blocked because it doesn't say it is (and that would be a big deal).

It's not "duplicating" darkness when it only works in very narrowly defined circumstances and can be trivially disrupted. If there are multiple light sources, or the light source is too distant and diffuse to be blocked by a 5-foot object (e.g., you're outside and the sun is up), or the enemy has darkvision, this trick doesn't work at all. And even if it does work, it fails the moment the light source moves! The person with daylight up only has to walk five feet on their turn, and the light pops right back out.

Sure, for minor illusion, a cantrip that just shut off daylight for a round. Use a larger aoe illusion or daylight not on a mobile object and it's even better. Esoecially because the lack of light diesn't affect the caster at all.

Most indoor light sources can already be shut off by a cantrip. Prestidigitation says explicitly that it can snuff out candles, torches, and campfires. True, it can't target magical light sources; on the other hand, a light source shut off by prestidigitation is really shut off and won't pop back up if somebody moves.

Non sequitur point is non sequitur.

Your foes can see that the area is (to them) pitch dark before they enter it. Why would they enter without a light source?

Easily solved. Cast it once they're in the area with your party behind the wall. Then your party advances through the wall, automatically disbelieving it while the enemy can't see them do this because it's dark.

Also, darkvision won't work because the area isn't dark, you only think it is, at keast according to your mind affecting illusion argument.

 

[Ovinomancer]

A lot of the reasoning for extremely limited illusion school spells I first saw back in the AD&D days, when due to lack of clearly defined boundaries, illusions ran roughshod over DMs' games because players would argue all sorts of insane abilities for illusions. The backlash seems to be a reaction out of concern that illusions can duplicate other more powerful spells, but to me, unreasonably so. All of these things (duplicating darkness or blindness, etc.) don't stand up to scrutiny, (HA!) when just physically interacting with the illusion pretty much breaks it. For Minor Image, putting an "illusion cardboard box on someone" means they step five feet right and break it immediately. Putting an "illusory cardboard box on yourself" gives you 'heavily obscured" -- ONCE. It then clues them in that you are using illusion magic, and the jig is up anyway. It's a poor man's 5 foot obscuring mist that uses your action, and which one person can dispel immediately without so much as a spell.

Then, if we get into more powerful illusions, such as Major Image, people use these arguments to completely defang these spells, which leads to the same situations as back in AD&D -- no one wanting to focus on illusion magic, because it is a pale facsimile (irony intended) of other schools of magic.

What's next, because "things can pass through" a Major Image, then putting a red dragon Major Image in front of a bonfire reveals it to be an illusion, because "the light passes through it?" It's a third level spell, yet a Web spell would outshine it because it's more effective at stopping a few orcs? To me, people need to focus on the specifics given in the spell description's mechanics -- namely, in the case of Major Image, it looks, smells, and sounds REAL, until you either TOUCH it, or decide to try and pierce it with an Investigation check.

Those are what would make illusion magics usable, and to start nitpicking until the whole school is useless eliminates the point the spell is in there for in the first place. When I hear talk of "proper clever use of the spells" to me it seems to frequently mean "use of the spells in extremely limited circumstances that only I think will work, that I see fit to allow" rather than making inferences that actually flow from what the spell says are its capabilities.

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?

Meanwhile, I adjudicate illusions as acting to achieve caster intent as much as possibke within the bounds of aoe and capability, so players on my game get good use out of illisions. They just don't block light sources or remove things from reality or force strange behavior to preserve the illusion. A pit illusion looks like a pit, but if you toss something in it skitters across the floor because the illusion can't remove it. But, if you cast an illusion of a pit in front of a real pit that you cover with the same illusion, you've got a really nasty trick going.

 

[Thyrwyn]

So... if a thing passes through the illusion, it is revealed. And light is a thing. Therefore illusions only work in total darkness.

Oh, air is also a thing. So illusions only work in total darkness, in a vacuum.

Gotcha.

Dissect the sentence again: it is not the instance of something passing through the image that reveals the illusion. It is the physical interaction. Implied by the context, is that said interaction has to be observed in order for it to be relevant, as in:

If person A turns away from the image of a wall and person B walks through it, person A would still see the image of the wall when they turned back around. Or, unless someone observes air and light passing through the illusion, only the air and light are aware that the wall is an illusion.

Note this is still consistent with my view that the image can exist and light can illuminate real objects on both sides of the image, even if the source of the light cannot be perceived.