A New Interpretation of Illusion Discernment Rules: Overpowered?

[Segev]

In another thread, there's a discussion going on over the usual debate regarding whether merely walking into an illusory fog cloud instantly reveals it to be an illusion due to that being "physical interaction." Leaving aside the usual argumetns, the analysis process led me to a third interpretation that is possibly even more powerful in favor of illusions, but takes the guesswork out of "should this automatically reveal it?" At the same time, it offers possibly more room for trying to give hints / excuses to TRY the Intelligence(Investigation) check without having the doublethink problem of "wait, why didn't the reason I'm looking just reveal it in the first place?"

This reading requires taking the entire paragraph as a whole:

"Physical interaction with the image reveals it to be an illusion, because things can pass through it. A creature that uses its action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the creature can see through the image."

In this interpretation, we must read the first two sentences together, as one: "Physical interaction with the image reveals it to be an illusion, because things can pass through it. A creature that uses its action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC." The first sentence establishes that physical interaction with the image can reveal it, since things will pass through it. The second explains how you go about determining that something has physically interacted with it. Under this interpretation, there is no automatic give-away; without spending your turn making an Intelligence(Investigation) check and succeeding against the spell DC, you do not notice any physical interactions that "go through it" in a way that reveals it. In other words, the first sentence explains what it is that the second sentence's mechanics are revealing to you. The third sentence then tells us what the consequences of it being revealed to be an illusion by the second sentence's action are.

Implications
This suggests, then, that there's no automatic detection for poking a sword into an illusory wall. Instead, the act of deliberately trying to do so would be how you flavor the Intelligence (Investigation) check. Because, let's be realistic, here: if a character is walking up to a wall and poking it on purpose, they already suspect it to be an illusion. (Okay, maybe they think it's trapped or something, but still, they're taking deliberate measures.) Anything they are doing that might incidentally result in "physical interaction" but which is not taking an action for the Intelligence(Investigation) check will not automatically reveal the illusion. It may give them hints as to there being "something up," but it won't automatically reveal it.

Illusory orcs will just happen to miss and dodge out of the way of earnest attacks; it takes the Intelligence(Investigation) check to recognize that the orc did not miss, or you did not miss the orc, and that the attacks passed through. The better the illusionist is (i.e. the higher the DC), the more convincing the orc's performance and the less opportunity to catch it clipping through you or your weapon.

Illusory walls being shot at by arrows will not automatically be seen to have the arrows passing through; in the confusion of earnest volleys or attacks, noticing that the arrows are actually passing through, and not bouncing off or passing over, is not automatic. You have to stop and watch closely to notice it, which is the action and the Intelligence(Investigation) check. Perhaps the illusion even has some reaction that makes it more realistic: maybe illusory arrows start appearing to stick in the wall, or there're illusory arrows bouncing off. A lack of visible arrows lying on the ground would be a hint that "something is up" and maybe you should look more closely at what's going on (i.e. take the action for the Intelligence(Investigation) check), and maybe the skill of the illusionist determines how much "extra" reaction the illusion can give to try to fool you (e.g. those illusory arrows appearing may not sync up perfectly with where the real ones pass through).

Illusory fog may or may not swirl, but whether the swirling or lack thereof, and the way it interacts with sounds and how well the enemy seems to be able to shoot out of it would provide a hint that "something is up," and then you could make the Intelligence(Investigation) check (as an action) to notice that it's not behaving "right." Maybe it's not blowing in the wind the way even magically-maintained fog does. Maybe it's not casting shadows quite right. Maybe you DO notice the arrows not causing the right kind of disruption. Assuming you make the DC.

(It is worth noting that the comments on the illusion "reacting" based on how good the illusionist is are not RAW, but rather possible fluff for the RAW that says that a higher DC makes any illusion harder to investigate and sus out.)

Illusory darkness balls might be hard to detect, but when you take a moment to think about them, you realize that your game is running on vantablack darkness, not ink blot darkness!

In any event, reading the entire paragraph holistically interprets the first sentence as telling you that physical interaction is how the illusion is revealed, and why; the second sentence is telling you the mechanics to engage with to detect the physical interaction that causes you to notice things going through the illusion.

Net Impact on the Power of Illusions
Under this reading of the RAW, illusions are stronger in a straightforward sense: no longer does simply interacting with it as if it were a real thing automatically reveal its falsity, even if you interact with it more directly than simply trying to avoid it. This is a boost, and one I think most who decry the weakness of illusions in general will find welcome. Now, the ONLY mechanical way to see through them (without spells or senses that automatically pierce it, anyway) is to spend an action and make the Intelligence(Investigation) check.

On the other hand, with the absence of automatic revelation based on "physical interaction," we no longer have great difficulty figuring out what could possible drive a creature to MAKE the Intelligence(Investigation) check without the illusion being automatically revealed. In fact, DMs should feel more free to point out discrepancies, because those discrepancies no longer are "and now you know for sure," but instead are hints that stopping to examine it may be wise. This is especially nice for DMs who struggle with fair play, because before they had to always be asking themselves if they are rendering illusions useless unfairly or not. Now, if they have a thing that might've (under other interpretations) automatically revealed the illusion, they can at least be assured that the NPC is only suspicious unless and until he takes the action and succeeds on the DC.

I think this makes for a more coherent spell, with less DM "mother-may-I" nature. It is definitely stronger in a game where the DM otherwise would have very often ruled that almost all illusions are auto-detected. It treats a paragraph about detection as a single unit, rather than as two separate units that hang together fuzzily around the third.

But, at the same time, I think by opening up freedom to have discrepancies and oddities that don't automatically cause the illusion to fail for all observers, it makes things easier to GIVE discrepancies and hints so that players and DM's NPCs can have more excuses to make the check.

And, finally, when the rules go out of the way to say that an action you can choose to take is how you completely overcome the illusion, I think it makes for a more consistent game and is probably closer to the intent. I suspect that illusions are INTENDED to require an action to see through, not to be a flimsy useless set of spells that are only useful in corner cases. I also suspect that it's intended that it be pretty easy to justify trying to take the action, rather than keeping creatures from taking the action being of critical importance due to how frail illusions are.

Questions and Discussion
So, what are your thoughts? Is this reading a logical one?

Perhaps most importantly: does this make illusions too powerful, especially if we assume it means it's easier to justify taking the action to see through them, because all the things that would "auto-reveal" under more piecemeal readings now instead provide some solid hints that "something is up?"

[Keltest]

I think this interpretation is entirely incorrect. Among other things, it means you fail to detect an illusionary boulder (or similar obstacle) after somebody physically pushes you inside of the illusion, since you never took your investigation check.

Let's say youre fighting a kraken, and youre standing in front of a boulder created with the spell that you dont know is an illusion. The kraken picks you up and throws you into the boulder, which it can see through with its truesight. What would happen under this interpretation?

[Segev]

I think this interpretation is entirely incorrect. Among other things, it means you fail to detect an illusionary boulder (or similar obstacle) after somebody physically pushes you inside of the illusion, since you never took your investigation check.

Let's say youre fighting a kraken, and youre standing in front of a boulder created with the spell that you dont know is an illusion. The kraken picks you up and throws you into the boulder, which it can see through with its truesight. What would happen under this interpretation?

Good question.

The straightforward answer is: you now have VERY GOOD REASON to suspect it's an illusion. If you don't take the time to make the Intelligence(Investigation) check, or if you fail it, you don't get to see through it by having it go faint, and you cannot be sure it's not something else that's causing the phenomenon.

To illustrate why this could be the case, let us consider the possibility (in the magic-heavy world of D&D) that this is an ethereal boulder, nonetheless visible on the material plane. I could honestly see a DM having a wizard or the like design a base that exists on both the ethereal and material planes, not-100%-overlapping, but with both sides visible on both planes. Kraken are powerful magical creatures who might have similar magical effects.

Is this common? No. Are illusions more common? Sure.



So, the net result, if it were an ethereal-but-visible-on-the-material-plane boulder would be that you can't make it go faint no matter how much you interact with it, because it really is blocking and reflecting light (or whatever it is you deem light and vision work by).


Now, back to the scenario you outlined: An illusory boulder the kraken throws you into when you didn't know it was an illusion.

If you wind up on the far side of it in an area you can see, presumably you will see the other side of the boulder, plus whatever is on the side you're on now. Let's say it's inside a cave with luminous lichen or coral. What you know is that the kraken grabbed you and threw you, and you flew towards a wall, and now you're here. If you have reason to recognize specifically that you were thrown at a boulder and that that is the far side of the boulder, perhaps you are now suspicious of that boulder. You can perform an Intelligence(Investigation) action to examine it. What happens if you fail the check? That's up to you and the DM to come up with as to WHY you can't tell the boulder is an illusion. My suggestion would be that the illusionist's skill is such that the boulder reacts in a way that denies you evidence of its illusory nature, but that isn't the only explanation. Mechanically, all you learn if you say your investigation effort is to walk into the boulder is that, indeed, you can walk into the boulder.

If you instead wind up inside the boulder, well, it's pitch dark in there. Darkvision won't help, either, other than to show you a black-and-white rendering of stone right up against your eyes (which probably is blurry-gray if not blurry-black). Devil's Sight will at least give you the color of the stone accurately, but not much more. It still takes an Intelligence(Investigation) check to try to figure out why you're blinded by this whatever-it-is, and reveal it to be an illusion.

Short answer: You know something is up and that you flew through the boulder; it still takes a successful Intelligence(Investigation) check to confirm it to be an illusion rather than some other weirdness. Note that nothing prevents successive actions and checks to prove what you suspect but haven't yet been able to really confirm.

[Keltest]

The fact that physical interaction is what reveals it to be an illusion would very strongly indicate that it is impossible for the illusion of the boulder to "react" in that manner.

Likewise, you have now created a scenario where your character knows the boulder is fake, and can treat it as fake, but doesnt actually know that its fake because they havent taken the time to intentionally poke it to make doubly sure that its fake even though they physically flew through/into it.

I think you've gotten so caught up on the questions of the edge cases that you forgot to account for normal usage of the spells.

[Segev]

The fact that physical interaction is what reveals it to be an illusion would very strongly indicate that it is impossible for the illusion of the boulder to "react" in that manner.

Likewise, you have now created a scenario where your character knows the boulder is fake, and can treat it as fake, but doesnt actually know that its fake because they havent taken the time to intentionally poke it to make doubly sure that its fake even though they physically flew through/into it.

I think you've gotten so caught up on the questions of the edge cases that you forgot to account for normal usage of the spells.

On the contrary, I think this handles normal usage much better. It allows you to have an illusory wall, boulder, goblin, dragon, etc. and not have it automatically fail because people interact with it at all.

The biggest problem with illusions is that if you treat the "Physical interaction" clause as absolute and automatic, rather than (as I suggest in this thread) treating the detection paragraph holistically, basically any illusion is almost self-cancelling just by existing in the world. DMs already have to be picky and choosy about what qualifies as "physical interaction," if they go with the automatic-revelation interpretation and don't want to simply soft-ban illusions by making them standing on the ground reveal them. The "take an action to roll Intelligence(Investigation)" rule also makes no sense, since the only reason you'd ever bother rather than just ignoring the thing is if you'd already determined it was an illusion and that you didn't care enough to walk over and stick your arm through it. But, if you don't care enough, why would you take the action?

For the "take an action to try to detect it" rule to make sense, you have to (a) be able to suspect it's an illusion, and (b) have a good reason not to do something that would automatically reveal it, like throw a rock at it.

Taking the paragraph holistically, (b) is handled by there being nothing that "automatically" detects it. You can strongly suspect - enough to take an action to throw a rock at it - but then you make the Intelligence(Investigation) check to see if you can discern that it is, in fact, illusory.



To turn this around: can you give me a non-edge, normal-usage case of the spell that you would use an action and an uncertain Intelligence(Investigation) check rather than simply doing a physical interaction that would automatically reveal it?

[Keltest]

On the contrary, I think this handles normal usage much better. It allows you to have an illusory wall, boulder, goblin, dragon, etc. and not have it automatically fail because people interact with it at all.

The biggest problem with illusions is that if you treat the "Physical interaction" clause as absolute and automatic, rather than (as I suggest in this thread) treating the detection paragraph holistically, basically any illusion is almost self-cancelling just by existing in the world. DMs already have to be picky and choosy about what qualifies as "physical interaction," if they go with the automatic-revelation interpretation and don't want to simply soft-ban illusions by making them standing on the ground reveal them. The "take an action to roll Intelligence(Investigation)" rule also makes no sense, since the only reason you'd ever bother rather than just ignoring the thing is if you'd already determined it was an illusion and that you didn't care enough to walk over and stick your arm through it. But, if you don't care enough, why would you take the action?

For the "take an action to try to detect it" rule to make sense, you have to (a) be able to suspect it's an illusion, and (b) have a good reason not to do something that would automatically reveal it, like throw a rock at it.

Taking the paragraph holistically, (b) is handled by there being nothing that "automatically" detects it. You can strongly suspect - enough to take an action to throw a rock at it - but then you make the Intelligence(Investigation) check to see if you can discern that it is, in fact, illusory.



To turn this around: can you give me a non-edge, normal-usage case of the spell that you would use an action and an uncertain Intelligence(Investigation) check rather than simply doing a physical interaction that would automatically reveal it?

Passive investigation. Its rarely used, but it is a thing. Theres even a feat that specifically boosts it.

Anyway, Under your interpretation, if somebody comes up to me, and tells me the rock is an illusion, and demonstrates it by walking through the rock, and drags me with them so I know for a fact its the rock and not them, if i fail that investigation check on my subsequent poke, then I'm still not convinced that the rock isnt real. Thats... fairly nonsensical.

[Segev]

Passive investigation. Its rarely used, but it is a thing. Theres even a feat that specifically boosts it.The spell does not permit you to use passive investigation unless you've stated that you are consciously and continually looking for illusions. Remember: you must take an action to do it; it is not something you get to do passively, per the spell.


Anyway, Under your interpretation, if somebody comes up to me, and tells me the rock is an illusion, and demonstrates it by walking through the rock, and drags me with them so I know for a fact its the rock and not them, if i fail that investigation check on my subsequent poke, then I'm still not convinced that the rock isnt real. Thats... fairly nonsensical.Perhaps. Let's go back to that ethereal rock. What happens if somebody comes up to you, tells you that rock is an illusion, demonstrates it by walking through the rock, and drags you with them so you know for a fact it's the rock and not them? Are you now CONVINCED it is an illusion, even though you're factually wrong?

[Keltest]

The spell does not permit you to use passive investigation unless you've stated that you are consciously and continually looking for illusions. Remember: you must take an action to do it; it is not something you get to do passively, per the spell.

Perhaps. Let's go back to that ethereal rock. What happens if somebody comes up to you, tells you that rock is an illusion, demonstrates it by walking through the rock, and drags you with them so you know for a fact it's the rock and not them? Are you now CONVINCED it is an illusion, even though you're factually wrong?

Sure, but it doesnt matter with an ethereal rock, because this hypothetical ethereal rock doesnt actually care what I think. The illusion, on the other hand, does. It becomes visibly transparent once I am convinced of its illusionary state.

[Segev]

Sure, but it doesnt matter with an ethereal rock, because this hypothetical ethereal rock doesnt actually care what I think. The illusion, on the other hand, does. It becomes visibly transparent once I am convinced of its illusionary state.

If there is an illusory boulder you have no reason to believe is illusory, and I cast suggestion to tell you, "That boulder is an illusion," do you automatically have the illusion revealed even if you don't take the action or fail the check, because "the illusion cares what you think?" You're 100% convinced it's an illusion, after all, and it happens to be true.

[Keltest]

If there is an illusory boulder you have no reason to believe is illusory, and I cast suggestion to tell you, "That boulder is an illusion," do you automatically have the illusion revealed even if you don't take the action or fail the check, because "the illusion cares what you think?" You're 100% convinced it's an illusion, after all, and it happens to be true.

Per Silent Image: "If a creature discerns the illusion for what it is, the creature can see through the image."

So yes, if you are magically convinced that something is an illusion, and it happens to be an illusion generated by Silent Image (or any other spell with such a clause) then it becomes transparent. The fact that your basis for being so convinced was wild and unrelated to the image itself is irrelevant, although it maybe speaks poorly of you if thats what it takes to get you to believe it.

[Segev]

Per Silent Image: "If a creature discerns the illusion for what it is, the creature can see through the image."

So yes, if you are magically convinced that something is an illusion, and it happens to be an illusion generated by Silent Image (or any other spell with such a clause) then it becomes transparent. The fact that your basis for being so convinced was wild and unrelated to the image itself is irrelevant, although it maybe speaks poorly of you if thats what it takes to get you to believe it.

I have bolded a key word there.

If we take that sentence alone, as you wish to take the first sentence in the same paragraph alone, then we can state that the character has discerned it to be an illusion simply by asserting, "You know, I don't think that's real." Now we never need the second sentence at all, since the moment you think to take the action, you have already discerned it to be an illusion, and thus it is faint.

At least, if we're to take anything that "convinces" you it's an illusion as "discernment."

[Dr.Samurai]

I can see this interpretation and I think I have even seen it in movies (though none immediately come to mind). Basically, something passes through something else but continues to appear real. Not until the characters move up to the thing and touch it (read: spend an action to investigate) do they perceive the illusion for what it is.

Is that the intent of the rules? I'm not sure. In a world of magic it could be intuitive that if something interacts strangely with another thing it's an illusion, so throwing something that passes through a wall could be enough.

But is seeing something pass through another object the same as discerning it's an illusion? I think generally, no.

[Telok]

I think this interpretation is entirely incorrect. Among other things, it means you fail to detect an illusionary boulder (or similar obstacle) after somebody physically pushes you inside of the illusion, since you never took your investigation check.

Isn't that the same logic behind casting invisibility and not being hidden because you didn't take the stealth action? The "it doesn't matter if you're unseen, without taking the action to hide everyone in the area knows where you are" type rulings.

[Keltest]

Isn't that the same logic behind casting invisibility and not being hidden because you didn't take the stealth action? The "it doesn't matter if you're unseen, without taking the action to hide everyone in the area knows where you are" type rulings.

No? Being hidden is actually a state defined in the rules, and invisibility alone doesn't get you all the way there. The Hide action is the easiest way to get the rest of the way there, but it's not the only way.

[Keravath]

Its an interesting different take on things. I don't think the wording really supports that interpretation but if a DM wanted to run illusions that way then it is their decision for their game.

The biggest issue I find with that approach is that an investigation check becomes a requirement even when something is obviously not real. If the suggested house rules were modified so that the ability to see through the illusion required a successful investigation but the nature of the illusion was revealed separately then that could also work.

i.e. I stand in a boulder - I know it is obviously not a real boulder - it is an illusion. However, if I want to be able to see through the illusion then I need to succeed on an investigation check. This sort of becomes a mental check of the creature creating the illusion vs the creature perceiving it. (Using Investigation(INT) as opposed to just a straight INT check). Belief in whether the image is an illusion or not is up to how the character interacts with it - the capability of seeing through the image is related to the investigation check.

Seems like a reasonable house rule to me but I don't think it is a justifiable interpretation of the spells as written.

[kazaryu]

not that its conclusive, but most of this just sounds like explanatory text in phantasmal force. where it explains that physical interaction with the illusion does *not* in fact reveal it. essentially in order to detect a phantasmal force as illusory you *have* to make the check. But if thats true for all illusions, why the extra text explaining it?

again, its not entirely conclusive, there are potential explanations. But it definitely creates a distinction.


Per Silent Image: "If a creature discerns the illusion for what it is, the creature can see through the image."

So yes, if you are magically convinced that something is an illusion, and it happens to be an illusion generated by Silent Image (or any other spell with such a clause) then it becomes transparent. The fact that your basis for being so convinced was wild and unrelated to the image itself is irrelevant, although it maybe speaks poorly of you if thats what it takes to get you to believe it.

the term 'discern' isn't synonamous with 'believe'. discerning something implies some form of logical progression, even if its faulty logic. (i.e. 'if she weighs the same as a duck, then shes made of wood, and therefore a witch'). Simply being forced to believe that something is true, would not be discernment. neither would assuming that something is true.

[heavyfuel]

To answer the question in the title: Yes, very much so.

This basically makes illusions into no save CC, forcing the enemy to first interact, which is definitely going to cost them something (probably an attack), then they also have to spend their entire Action next round to maybe make the Investigation DC.

On a personal note, if I shoot at a boulder and the arrow goes into the boulder without making a sound and the DM says I don't know it's an illusion, I'll kindly tell him to shove it and metagame the crap out this interaction.

[Telok]

No? Being hidden is actually a state defined in the rules, and invisibility alone doesn't get you all the way there. The Hide action is the easiest way to get the rest of the way there, but it's not the only way.

Hmm. Perhaps I didn't phrase it well. Its the way the rules are approached, not the specific rules. These rules are followed with such specificity and attention to detail usually only when the pcs are trying to gain an advantage over the npcs. You'll see this all through modules and forums, the pcs have to roll to succeed and every possible rule is brought up to stop them because the game wouldn't be fun if they just flat out won once in a while. But its not applied to npcs because the dm needs stuff to work for the plot.

You can't use illusions on grass or near bushes or mud or on windy days or jn strong light, because stuff goes through (illusions don't cast shadows) and autofails it for everyone in sight. You can't use them in combat because anything interacting with it at all in any way autofails it for everyone on the map. You can't do this, you can't do that... its no wonder I never see anyone take or use them. But if they show up in a module or the dm uses one somewhere it works fine.

Same with hiding. Check any ambush or surprise type encounter in a module, there will likely be a dc 15+ check to spot it. Check the modules for stealth escapes, the npc goes invis and runs off so the pcs get to guess where they went and make perception checks. But when a pc tries it they have to roll because the rule says unseen and unheard so you gotta make a check even if you're sitting still invis on a flying broom 200 feet up and if you roll a 3+7 too bad everything with a 10+ passive perception knows where you are. But a bunch of kobolds in a hay loft? Dc 20 roll if you said you were looking.

The patterns of using rules like 'anything that touches the illusion breaks it' and 'you have to make a stealth check to be hidden' is that this pendantic insistence on "following the rules" only comes up when its being used against the players. Dms don't have npc's illusions instantly fail from random environmental effects or an ambush be a flop because a couple npcs rolled low to hide.

[CapnWildefyr]

The interactive autofail is too much. A better approach, not in the rules of course, is something along the lines of what your propose:

Physical interaction can grant you an investigation check. If you succeed, you see it's an illusion.
You can get passive investigation checks automatically, depending on circumstances. For example, being thrown through an illusionary boulder.
When conditions cause you to interact with stupid, you get advantage. For example, as you can't stand on a boulder, you get a check (passive or active, probably not taking your action either way) at advantage. if you roll a 1, you move your character to the side of the boulder and tell yourself it was slippery and you fell off it, or it was too hard to climb. (Rationalizing the spell.) If you get thrown through the illusionary boulder and fail your check (with advantage) you assume you bounced off it, or rolled over it. Or don't think about it at all.
Anyone telling you it's an illusion either lets you make another check with advantage. Again, a free check, doesn't take an action.
If you fail your check, your mind rationalizes what's happening. You try to open an illusion of a door. When your hand touches the "handle," you get a save (with advantage). If you fail, the fact that the door handle is fake doesn't register. When your hand goes through it, you think to yourself "I guess the door's a pusher, not a puller" or whatever. Maybe you think it was too hot to touch. Anything to momentarily rationalize what your eyes tell you is there over what your hand said was not there. The magic of the spell clouded your thoughts.
If it's a concentration spell, and the caster is clever, the caster can adapt it to circumstances because it's ongoing. The caster can make the illusionary fog swirl, or the illusionary boulder get split, or whatever. That keeps up the illusion, and provides rationale for ongoing saves. However, the DM has to take into account whether the caster would be able to make the illusion adapt reliably. this introduces the possibility of DM error: The DM thinks, "Sure this guy would have seen a red dragon, so the red dragon's flames would look real" but the players might be thinking something else, like "Why would the flames from the dragon not be melting the rocks, like the DM said last time? We would have noticed that, you should have given us that as a clue, no fair!"
Maybe the level of the spell impacts its ability to adapt. The problem here is that the system is not set up in a way to help us make distinctions between, say, the number of senses in the illusion, and the ease at which you can tell it's an illusion, or whether you save with advantage.


Those of you who played earlier editions make think this is similar to them, and it is. It was problematic back then, too. The biggest issue is that what a player and a DM think is incredibly obvious are not the same thing, Under the current rules, though, illusions are weak because almost ANYTHING makes them useless. I'd prefer a setup where the magic of the illusion actually does something besides make a pretty hologram, where the magic affects the mind and you have to actively try to get beyond it. I mean, you have to actively resist/interact with fireball, and wall of force, and ice storm. Why not more power for illusions as well?

Under the current system, many illusions are lame unless you can keep them away from the targets. Can you imagine fireball autofailing if the target is wet, or too sweaty?

[GooeyChewie]

I think the intention is that you can figure out something is an illusion simply by interacting with it in a way that wouldn't make sense for the real thing, but it only because transparent once you've succeeded at the Investigation check. In the case of fog, I would say that the characters don't "interact" with it simply by walking through it, since you can walk through regular fog. But if the characters run into fog in an unexpected place, it's reasonable for them to investigate it (which I would likely describe as waving their hands around and realizing the fog isn't curling around them) to recognize it as an illusion. If successful, then the fog becomes transparent. If unsuccessful, the character just thinks its weird fog, probably assuming it was magically conjured but not an illusion. Of course, if any party member succeeds, they could tell the others to continue investigating, and if the party is under no time pressures they will eventually get it, so that point I would probably not require any more actual rolls. Illusions are most powerful when you fashion them in such a way that others don't even question the illusion. (Disclaimer: All of this is just how I think it should be run. I have not given it a pass through RAW to see if it agrees.)

[MoiMagnus]

I'm always annoyed with the way illusion works in D&D.

Like, if you see a boulder appear out of nowhere in front of you, sure, magic exists so it could have been created out of thin air. But on the other hand, creating an illusion being much easier, much lower level, so much more common, so shouldn't anyone living in the universe first behave as if the boulder was an illusion until proven real?

Which lead me to three possibilities:

Illusion spells include a mental effect that force you to believe in it. In which case it's reasonable for you to still believe in the boulder being real even if you see some absurd things (like going through the boulder and still being convinced it is real) up until you take the time to really think about it (action to make an Investigaction check) to counteract this mental effect. => This would follow Segev's interpretation.
Illusion spells don't include a mental effect, in which case in a lot of circumstances peoples will guess the boulder is an illusion just by seeing it appear out of nowhere, and since it's a correct guess then that mean that they can now see through it => I don't like this possibility as it makes illusion way too weak.
Illusion spells don't include a mental effect, but just guessing that something is likely an illusion is not enough to see through it. The "disbelieving" trigger that allows you to see through it is actually difficult to reach, as you really need to find a flagrant contradiction by interracting with it that has no other explanation than "this is an illusion". => This has a wide margin of interpretation depending on how hard to reach this trigger is.

[Keltest]

I'm always annoyed with the way illusion works in D&D.

Like, if you see a boulder appear out of nowhere in front of you, sure, magic exists so it could have been created out of thin air. But on the other hand, creating an illusion being much easier, much lower level, so much more common, so shouldn't anyone living in the universe first behave as if the boulder was an illusion until proven real?

Which lead me to three possibilities:

Illusion spells include a mental effect that force you to believe in it. In which case it's reasonable for you to still believe in the boulder being real even if you see some absurd things (like going through the boulder and still being convinced it is real) up until you take the time to really think about it (action to make an Investigaction check) to counteract this mental effect. => This would follow Segev's interpretation.
Illusion spells don't include a mental effect, in which case in a lot of circumstances peoples will guess the boulder is an illusion just by seeing it appear out of nowhere, and since it's a correct guess then that mean that they can now see through it => I don't like this possibility as it makes illusion way too weak.
Illusion spells don't include a mental effect, but just guessing that something is likely an illusion is not enough to see through it. The "disbelieving" trigger that allows you to see through it is actually difficult to reach, as you really need to find a flagrant contradiction by interracting with it that has no other explanation than "this is an illusion". => This has a wide margin of interpretation depending on how hard to reach this trigger is.


"I disbelieve in the X" has become shorthand among my older group for "I'm screwed and I know it, but I can't think of a way out of this situation."

I agree that D&D could use some more illusions that work like Phantasmal force, but its also low key one of the strongest illusion spells in the game in terms of sheer latitude the caster has to do whatever they want.

[Unoriginal]

I'm always annoyed with the way illusion works in D&D.

Like, if you see a boulder appear out of nowhere in front of you, sure, magic exists so it could have been created out of thin air. But on the other hand, creating an illusion being much easier, much lower level, so much more common, so shouldn't anyone living in the universe first behave as if the boulder was an illusion until proven real?

Which lead me to three possibilities:

Illusion spells include a mental effect that force you to believe in it. In which case it's reasonable for you to still believe in the boulder being real even if you see some absurd things (like going through the boulder and still being convinced it is real) up until you take the time to really think about it (action to make an Investigaction check) to counteract this mental effect. => This would follow Segev's interpretation.
Illusion spells don't include a mental effect, in which case in a lot of circumstances peoples will guess the boulder is an illusion just by seeing it appear out of nowhere, and since it's a correct guess then that mean that they can now see through it => I don't like this possibility as it makes illusion way too weak.
Illusion spells don't include a mental effect, but just guessing that something is likely an illusion is not enough to see through it. The "disbelieving" trigger that allows you to see through it is actually difficult to reach, as you really need to find a flagrant contradiction by interracting with it that has no other explanation than "this is an illusion". => This has a wide margin of interpretation depending on how hard to reach this trigger is.


Some DnD illusions are mental effects that "force" you to believe its real, by making all your senses scream at you it's real.

Most illusions do not include mental effects, though, and they simply appears to be real until you either do something that disprove it (touch the boulder, hand goes through) or if you investigate to see the ways the illusion is imperfectly reproducing reality.

Just getting a hunch something isn't real isn't enough to disbelief the illusion.



in which case in a lot of circumstances peoples will guess the boulder is an illusion just by seeing it appear out of nowhere

I mean in the world of DnD, making boulders appear isn't that unbelievable.

[PhantomSoul]

Just getting a hunch something isn't real isn't enough to disbelief the illusion.

And certainly not the higher bar of discerning it isn't real as opposed to just questioning its "real" status!



I mean in the world of DnD, making boulders appear isn't that unbelievable.

Not guaranteed nonsense, but it's still a fair point that illusions are probably more accessible than proper comparable conjurations (not that that means they're more common, e.g. if there's some stigma against illusions)

[CapnWildefyr]

I'm always annoyed with the way illusion works in D&D.

Like, if you see a boulder appear out of nowhere in front of you, sure, magic exists so it could have been created out of thin air. But on the other hand, creating an illusion being much easier, much lower level, so much more common, so shouldn't anyone living in the universe first behave as if the boulder was an illusion until proven real?

Which lead me to three possibilities:

Illusion spells include a mental effect that force you to believe in it. In which case it's reasonable for you to still believe in the boulder being real even if you see some absurd things (like going through the boulder and still being convinced it is real) up until you take the time to really think about it (action to make an Investigaction check) to counteract this mental effect. => This would follow Segev's interpretation.
Illusion spells don't include a mental effect, in which case in a lot of circumstances peoples will guess the boulder is an illusion just by seeing it appear out of nowhere, and since it's a correct guess then that mean that they can now see through it => I don't like this possibility as it makes illusion way too weak.
Illusion spells don't include a mental effect, but just guessing that something is likely an illusion is not enough to see through it. The "disbelieving" trigger that allows you to see through it is actually difficult to reach, as you really need to find a flagrant contradiction by interracting with it that has no other explanation than "this is an illusion". => This has a wide margin of interpretation depending on how hard to reach this trigger is.


The mental effect is where I was coming from in my post. An illusion without a mental effect is a cheap evocation I guess, or maybe conjuration. Illusion spells that don't affect the mind shouldn't be called "illusions" but without checking the spell lists, I bet they are even though there's no "mental" part noted. They've become holograms. Even major image, at 3rd level, goes away if you touch it in any way. It's called an illusion, but really it's a light show. A real illusion should only appear in the minds of the affected, not actually exist.

[Unoriginal]

The mental effect is where I was coming from in my post. An illusion without a mental effect is a cheap evocation I guess, or maybe conjuration. Illusion spells that don't affect the mind shouldn't be called "illusions" but without checking the spell lists, I bet they are even though there's no "mental" part noted. They've become holograms. Even major image, at 3rd level, goes away if you touch it in any way. It's called an illusion, but really it's a light show. A real illusion should only appear in the minds of the affected, not actually exist.

Illusions have always been both lightshows, holograms and mental effects.

If you think that an hologram makes illusion "cheap evocation", why is a mental illusion not "cheap enchantment"?

[Segev]

The biggest issue I find with that approach is that an investigation check becomes a requirement even when something is obviously not real. If the suggested house rules were modified so that the ability to see through the illusion required a successful investigation but the nature of the illusion was revealed separately then that could also work.1) I am claiming that this is not a house rule, but in fact is how the RAW can be read. It would be a ruling, not a house rule. (In fact, the more I've thought about it, the more I've become convinced that this is the most accurate ruling, but I do not claim it is the only possible one.)

2) That said, what you outline is how I see it working. If you get flung through that boulder, you may well strongly suspect that it is an illusion, and then use an action to make an Intelligence(Investigation) check to figure out the flaws that let you see through it. Or let you prove it, or however the "and now you see through it" works in-story.

I have no problem with the action being a requirement to see through it; if the creature decides that ogre is no threat because it can't hit the broad side of a barn and chooses to ignore it without actually spending the action, or if he realizes he can walk through that boulder without stopping to examine it so he can see through it, it still obscures vision, but it's not like it's forcing him to treat it as if it has properties it doesn't. He can walk through it or ignore it or whatnot.

This only becomes an issue if there's a reason seeing through it is necessary, such as being able to pick out the illusory orcs from the real ones, or needing to see the people hiding inside the illusory darkness or behind the illusory wall (possibly with arrow slits).


not that its conclusive, but most of this just sounds like explanatory text in phantasmal force. where it explains that physical interaction with the illusion does *not* in fact reveal it. essentially in order to detect a phantasmal force as illusory you *have* to make the check. But if thats true for all illusions, why the extra text explaining it?

again, its not entirely conclusive, there are potential explanations. But it definitely creates a distinction.That's a good point, but I think looking at it in light of Keravath's discussion above is helpful: Nothing in silent image or even major image compels a creature to act like the illusion is real, even if they aren't able to see through it. A major image of an iron cage will look and even feel real, but if the character simply walks through it, he can. A phantasmal force compels him to rationalize things about the illusion; he didn't walk through it - he's still trapped! Or maybe he isn't, but the cage was unlocked. This actually makes creature phantasmal forces even better than object/trap ones: The ogre he's fighting isn't suspiciously dodgy; he just has a LOT of hit points.

Phantasmal force actually has rules against using inconsistencies to justify making the check; Bob almost HAS to be told "it's an illusion, Bob," to justify making the check, unless he has other reasons to sit and Intelligence(Investigate) the illusion (perhaps to try to find traps or pick a lock). Otherwise, he's compelled to act like it's real, and justify to himself anything that he can't play-act effectively enough. (Personally - and this is probably a thread of its own worth of discusison - I would argue that "iron cage" phantasmal forces do not permit the creature to walk out. They try the bars and convince themselves they're real. They fling themselves at said bars, and subconsciously stop themselves from moving beyond them (or at least convince themselves they haven't as they "bounce back" away from them).)


To answer the question in the title: Yes, very much so.

This basically makes illusions into no save CC, forcing the enemy to first interact, which is definitely going to cost them something (probably an attack), then they also have to spend their entire Action next round to maybe make the Investigation DC.

On a personal note, if I shoot at a boulder and the arrow goes into the boulder without making a sound and the DM says I don't know it's an illusion, I'll kindly tell him to shove it and metagame the crap out this interaction.Nothing in silent image compels you to treat a boulder that you can clearly see is intangible as if it's intangible. If you want to see through it, you spend the action and make the check. If you don't care, then you know what you saw.

If I'm the DM, and you're shooting arrows into boulders to test their tangibility, I'd probably let that count as the action to make the Intelligence(Investigation) check. It's not like you were trying to do anything BUT validate the reality of the boulder, were you? Fail the check, and something about how you shot the arrow means that it didn't obviously slide silently into the boulder; you didn't see what you were looking for and didn't get your confirmation.


I think the intention is that you can figure out something is an illusion simply by interacting with it in a way that wouldn't make sense for the real thing, but it only because transparent once you've succeeded at the Investigation check. In the case of fog, I would say that the characters don't "interact" with it simply by walking through it, since you can walk through regular fog. But if the characters run into fog in an unexpected place, it's reasonable for them to investigate it (which I would likely describe as waving their hands around and realizing the fog isn't curling around them) to recognize it as an illusion. If successful, then the fog becomes transparent. If unsuccessful, the character just thinks its weird fog, probably assuming it was magically conjured but not an illusion. Of course, if any party member succeeds, they could tell the others to continue investigating, and if the party is under no time pressures they will eventually get it, so that point I would probably not require any more actual rolls. Illusions are most powerful when you fashion them in such a way that others don't even question the illusion. (Disclaimer: All of this is just how I think it should be run. I have not given it a pass through RAW to see if it agrees.)
I largely agree with this.

The key point is that "physical interaction reveals it because things go through it; you can tell that things went through it in impossible ways by spending an action and probing it to make an Intelligence (Investigation) check" is the reading I'm giving it. As opposed to, "Physical interaction automatically reveals it to be an illusion. Absent physical itneraction, you can spend an action making an Intelligence(Investigation) check to reveal it," which tends to be the other way to read it. (Well, or the way I used to read it: "Physical interaction automatically reveals it to be an illusion if the physical interaction caused something to go through it in a way that was impossible for the real thing. Failing that, you can also spend an action on an Intelligence(Investigation) action to realize it even if you can't create an obviously-impossible physical interaction." But I think the interpretation I have outlined in this thread is actually superior to that, now: it follows the typical pattern of how rules in 5e are written, and addreses the whole paragraph as one rule rather than trying to mince it apart into two separate rules that somehow both use the third sentence rather than three separate rules where the third sentence overrides the other two.)

Some discussion on why I think this interpretation also improves the game as a level playing field.

Even very fair DMs have to juggle cognitive load when it comes to illusions and enchantments. "How would my creature really act if this were real, rather than an illusion/rather than him being wrong about how he feels?" Ignoring enchantments for a moment, though, let's focus on the doublethink involved in trying to determine how an illusion should influence creatures. And also on how PLAYERS interact with illusions.

A DM necessarily knows what is and is not illusory. He has to. Players only know what is illusory if they create them, or if they detect them somehow. An illusion the DM describes as part of the scene will not, to the players, be called out in any way, unless the DM has reason to give it away for free. This means that the players who see the illusory ogre or the illusory wall will generally treat them as real. On the other hand, the DM knows they're illusory and has to determine if that ogre would get attention or not, and whether that wall would be tested or not, and...well, all sorts of things.

This doesn't perfectly handle it, but it puts things on a little more even playing field: At the very least, it compels NPCs to spend actions to get the "see-through" effect rather than permitting them free "see-through" based on a "physical interaction" that they may or may not have made or even questioned if the DM didn't know that there was an illusion. Similarly, it frees the DM from having to stop and ask himself, "Wait, did what they just do count as physical interaction that should out and out reveal the illusion? How do I hint enough that it's an illusion to even let them know that an Intelligence(Investigation) action migth be worthwhile?"

With this paradigm, you can strongly suspect an illusion, and may choose to act as if you're certain it's an illusion (because you all but are), but you can't get the free see-through without the Intelligence(Investigation) check.