D&D 5E Invisible Objects and Spell Effects under RAW

[Ashrym]

The only RAW I can think of is perception checks based on sight auto-fail. Beyond that it's the approach of the players and DM's interpretation on how hard a check should be.

 

[Oofta]

The definition of invisibility is from the perspective of a creature, so I only look at the parts I've bolded:

An invisible creature is impossible to see without the aid of magic or a special sense. For the purpose of hiding, the creature is heavily obscured. The creature's location can be detected by any noise it makes or any tracks it leaves. ​

​

So if the only way to detect it is visual? Not going to happen. It's impossible. You have to literally touch it or interact with it in some way.

Other than that it depends on the object. A wall or big enough might be detectable (at a very high DC) because of sound bouncing off of it. A mechanical device such as a clock could be making sound. Otherwise there has to be something in the environment external to the object that can be detected. But it will be impossible to detect visually.

 

[FrogReaver]

In 5E, invisible creatures are not hidden by default. Even though you're invisible, until you take the hide action, your location is obvious due to your sounds, tracks, etc... We don't all like the rule, but it is there.

What about invisible objects or spell effects? If a cup is made invisible, what needs to be done to detect the presence of it on a table? What does a creature need to do to detect an arcane eye or rope trick portal?

From what I can tell, you fall back to generic rules of setting a perception DC to perceive something that is hard to spot under the RAW - perhaps a DC of somewhere between 15 and 25. Is that how you'd handle the PCs attempting to detect an arcane eye, a rope trick portal, a scrying sensor or an invisibile object on a table?

Consider a cup. If it's not moving and is invisible then sight won't reveal it's existence.

 

[Oofta]

Consider a cup. If it's not moving and is invisible then sight won't reveal it's existence.

Exactly. Unless you bump the table and hear something fall over or see a clean circle on an otherwise dusty table or cobwebs attached to nothing you aren't going to detect it.

Unless, of course it starts talking to you.

 

[FrogReaver]

Exactly. Unless you bump the table and hear something fall over or see a clean circle on an otherwise dusty table or cobwebs attached to nothing you aren't going to detect it.

Unless, of course it starts talking to you.
View attachment 115403

My problem with invisible items is that once players learn of their existence there are simple mundane ways to check for them at the cost of a trivial amount of time.

Then there's also the detect magic spell/ritutal.

In short, static invisibility (unless part of a puzzle) is pretty boring.

 

[Oofta]

My problem with invisible items is that once players learn of their existence there are simple mundane ways to check for them at the cost of a trivial amount of time.

That and as was posted above, what purpose does the item serve in the game? Even assuming it's just a "nice to have" the DM sets whatever DC makes sense and then justifies being able to detect it because of some external environmental factor. That can be anything from automatic (you touch it after you see a noisy bird sitting on nothing) to nearly impossible (moats of dust in the air moving oddly).

 

[FrogReaver]

That and as was posted above, what purpose does the item serve in the game? Even assuming it's just a "nice to have" the DM sets whatever DC makes sense and then justifies being able to detect it because of some external environmental factor. That can be anything from automatic (you touch it after you see a noisy bird sitting on nothing) to nearly impossible (moats of dust in the air moving oddly).

For a single item in the campaign done that way, that's probably fine - since at that point it's probably more of a puzzle. But if invisible items are encountered more than once then players will start checking for invisible items everywhere.

 

[Esker]

In 5E, invisible creatures are not hidden by default. Even though you're invisible, until you take the hide action, your location is obvious due to your sounds, tracks, etc... We don't all like the rule, but it is there.

What about invisible objects or spell effects? If a cup is made invisible, what needs to be done to detect the presence of it on a table? What does a creature need to do to detect an arcane eye or rope trick portal?

From what I can tell, you fall back to generic rules of setting a perception DC to perceive something that is hard to spot under the RAW - perhaps a DC of somewhere between 15 and 25. Is that how you'd handle the PCs attempting to detect an arcane eye, a rope trick portal, a scrying sensor or an invisibile object on a table?

In the case of an object created or made invisible by a spell, wouldn't the caster's spell DC be the obvious choice of DC to detect its presence, provided there is a plausible source of evidence about its existence?

Perception checks based on sight automatically fail, but if the object is moving (like an arcane eye), there might be disturbances to the air, which perception (at disadvantage) could pick up on. But then figuring out what it actually is might require further action (detect magic, see invisibility, maybe an arcana check to make the inference).

If it's a static object in a room, I'd probably reveal its existence as part of a sufficiently high investigation roll to search the room rather than a perception check, since finding it is more of an inference than it is a sensory thing.

But in each case, I'd use the caster's DC, with advantage or disadvantage applied to the check depending on the situation.

 

[FrogReaver]

In the case of an object created or made invisible by a spell, wouldn't the caster's spell DC be the obvious choice of DC to detect its presence, provided there is a plausible source of evidence about its existence?

IMO. It's either invisible or not. Better casters don't make objects more invisible than worse ones.

Perception checks based on sight automatically fail, but if the object is moving (like an arcane eye), there might be disturbances to the air, which perception (at disadvantage) could pick up on. But then figuring out what it actually is might require further action (detect magic, see invisibility, maybe an arcana check to make the inference).

right

If it's a static object in a room, I'd probably reveal its existence as part of a sufficiently high investigation roll to search the room rather than a perception check, since finding it is more of an inference than it is a sensory thing.

I wouldn't unless they had indicated they were investigating the table the invisible cup was sitting on and doing more than looking at it while doing so.

But in each case, I'd use the caster's DC, with advantage or disadvantage applied to the check depending on the situation.

I would not. There are not degrees of invisibility. There is invisible and there is not. I would solely base the DC on environmental factors and players stated actions.

 

[Esker]

IMO. It's either invisible or not. Better casters don't make objects more invisible than worse ones.

Yeah, I suppose with the invisibility spell cast on a creature, the perception threshold is the stealth roll rather than the caster's DC. But in the case of a spell like arcane eye, since the eye doesn't have stats and the spell doesn't give a DC, it makes sense to me to say that the better the caster, the less the eye disturbs its environment. But maybe an even better way to handle it would be to have the caster make a stealth check using their casting stat in place of dexterity.

I wouldn't unless they had indicated they were investigating the table the invisible cup was sitting on and doing more than looking at it while doing so.

I think it comes down to what level of detail the DM likes to give of the environment, and what level of player specificity they require for something like searching a room. The investigation skill is supposed to capture the character's ability to make inferences from evidence, and it could well be that the character could do a better job than the player at knowing what to look at. It's a bit like when a character makes a persuasion or deception check; how much do you let the player's facility with rhetoric influence the outcome if they're playing a character that's much more skilled than they are?