D&D 5E Guidance on Illusion spells

[jaelis]

I would agree with your DM that if you attack the illusion and roll reasonably well, then you know it is an illusion. Whether the timing would allow the other monsters to change targets is really just up to the DM. I probably would play it like you saw, on the basis that if you'd really summoned a creature and the first attack killed it, I wouldn't make other monsters waste arrows on the corpse.

 

[AaronOfBarbaria]

That is kinda what happen at first .. I told the DM they have to make a DC Saving throw and they all failed. but when the one Gnolls turn came up he attacked it and then magically they all knew they it was a fake unicorn

You stating how it went down again has pointed out to me another area where things weren't handled strictly by the book.

When you cast an illusion spell, no one makes a roll - whatever the illusion is, it is just there and everyone viewing it defaults to not being aware of it being an illusion.

Then they actually do something, and maybe they figure out it is an illusion.

The spells aren't worded to support a roll the instant they come into being and then also more rolls later, just the later rolls that normally take up an action to make.

 

[nswanson27]

You stating how it went down again has pointed out to me another area where things weren't handled strictly by the book.

When you cast an illusion spell, no one makes a roll - whatever the illusion is, it is just there and everyone viewing it defaults to not being aware of it being an illusion.

Then they actually do something, and maybe they figure out it is an illusion.

The spells aren't worded to support a roll the instant they come into being and then also more rolls later, just the later rolls that normally take up an action to make.




This is what I thought should happen as well ... they all attack it or run over to capture it, thus the party avoids 1x or 2x rounds of their attacks

I had this sorta thing happen to me, where the DM had the mobs do an investigation check when I cast an illusion of myself. The term "DM metagaming" comes to mind.

 

[AaronOfBarbaria]

I had this sorta thing happen to me, where the DM had the mobs do an investigation check when I cast an illusion of myself. The term "DM metagaming" comes to mind.

I wouldn't jump to the conclusion that the DM is intentionally doing things wrong in an effort to get one over on the players.

It seems very likely, considering that most other spells don't use the same procedure of "it automatically works when cast, but can be thwarted later", that the DM simply doesn't realize they aren't following the written rules.

 

[Gadget]

First of all, there is no initial save for Silent Image, so I'm confused what the original post means by "each of the 3x all failed their spell save DC". Once the spell is cast, the image manifests, and appears to witnesses as real unless they take an action to investigate it using an intelligence check or they physically interact with it. I don't find the DM's ruling out of line, as seeing an arrow pass through the illusion would definitely count as "physical interaction", just as entering melee with the illusion would entail physical interaction. Having the monster roll to attack is (say an AC 11) seems plausible. The illusion served its purpose as a distraction, causing the monster to 'waste' a round's action shooting at the image (assuming it 'hit' the AC set by the DM). Where there might be some room for argument would be if the rest of the monsters noticed in the chaos of the combat or not.

The argument that it appears that the monster just missed the target until they make their investigation check appears to have merit at first blush, I would definitely consider that at long ranges/poor visibility, but this seems to be giving more power than is warranted to the spell. For instance, if the monster had entered melee with the image, would it appear to the monster that he just kept whiffing? No sound or tactile sensation, but the image just keeps moving out of the way at the last instant? Is the caster somehow causing this fine detailed control? If so, I hope the caster is spending an action for this effect as the spell says: "You can use your action to cause the image to move to any spot in range." This would definitely fall under the category of "movement" in my book, though I think it is debatable that this level of control is implied by the statement.

Another example: Say you cast the spell to represent a boulder, tree, or box of some type that the rogue, McStaby, proceeds to hide in with his trusty short/cross bow. McStaby then proceeds to shoot out of it as the monsters approach, for full sneak attack damage due to advantage from Hiding. Great! The monsters may even be surprised. "Hey where did that arrow come from? Somewhere over there! Ouch, Bill is hit!" At some point, the monsters have to notice the arrows shooting directly out of a boulder/tree/box and the game is up. Is this physical interaction? Is the spell basically in place invisibility a level early, due to the fact that many monsters don't have an investigate bonus or an intelligence bonus? Perhaps many DM's would give a bonus to any investigate check made under these circumstances, if not outright rule that seeing an arrow come out of an inanimate object counts as physical interaction.

I guess the bottom line is, as always, go with what works at your table. For new/inexperienced/young role players, it would be nice to give them some leeway for these spells; but for hard bitten min/maxing power gamers, not so much.

 

[Uller]

A successful attack is most definitely a "physical interaction" and would reveal it to the attacker. I'd give any creatures observing that a new save (combat is confusing so I don't think someone seeing an arrow pass through the illusion might not be enough)

Keep in mind also that the spell is _silent_. A horse appearing out of nowhere in the middle of melee that makes no noise at all is a bit suspicious and I think the DM is his/her right to question the effectiveness of the tactic and I might be inclined to give observers advantage on the save due to the lack of noise. You probably should consider that when you choose your illusion.

A first level utility spell potentially causing a wasted an attack is probably fair. That's about the same as a Cure Wounds spell right?.

 

[Uller]

A successful attack is most definitely a "physical interaction" and would reveal it to the attacker. I'd give any creatures observing that a new save (combat is confusing so I don't think someone seeing an arrow pass through the illusion might not be enough)

Keep in mind also that the spell is _silent_. A horse appearing out of nowhere in the middle of melee that makes no noise at all is a bit suspicious and I think the DM is his/her right to question the effectiveness of the tactic and I might be inclined to give observers advantage on the save due to the lack of noise. You probably should consider that when you choose your illusion.

A first level utility spell potentially causing a wasted an attack is probably fair. That's about the same as a Cure Wounds spell right?.

 

[AaronOfBarbaria]

A successful attack is most definitely a "physical interaction" and would reveal it to the attacker.

How do you determine if an attack is successful against something that doesn't have an AC?

 

[Uller]

How do you determine if an attack is successful against something that doesn't have an AC?

I was more just reacting to the OP. Typically I read "physical interaction" as simply attacking it. It's not like it could parry or use a shield or armor. But if I felt a need to assign an AC (maybe instead of a large image the illusion is a small agile pixie), the highest I would make the AC would be the same as the save DC for the caster. Like I said...using a first level utility spell to negate an attack is pretty fair. I could probably be convinced that attacking it simply results in another intelligence save. Dumber monsters might take longer to figure it out. But they also would quickly figure out their attacks are not effecting it and it isn't hurting them.

 

[Saeviomagy]

You cast a first level spell and burned an opponents action. That's not terrible.

I think the only problem is this: the creatures should not have had an initial save.

Outside of that, I think your DM was in the right. The spell says that "Physical interaction with the image reveals it to be an illusion, because things can pass through it.". Shooting something is clearly a physical interaction, and the reveal isn't limited to only the interactor. In future you need to create illusions that monsters aren't just going to shoot at OR (with your DM's cooperation) illusions that could feasibly have objects pass through them. An illusion of a ghost wouldn't be determined to be an illusion for instance (although the monsters may still not waste attacks on something they can't hit).