D&D 5E Finding Invisible Objects and Spell Effects

[jgsugden]

There are several things in D&D that are not creatures but are invisible... The portal of a Rope Trick. The Arcane eye's arcane eye.

As a DM, how do you determine if the PCs can perceive these things without the aid of see invisible or similar magics? The rules are silent on perceiving invisible objects as the rules all focus on seeing invisible creatures.

Do you treat them like hidden objects and allow a perception check?

Do you not allow it to be perceived unless someone walks into it (or uses magic to find it)?

Or did I miss a rule somewhere?

 

[Ovinomancer]

There are several things in D&D that are not creatures but are invisible... The portal of a Rope Trick. The Arcane eye's arcane eye.

As a DM, how do you determine if the PCs can perceive these things without the aid of see invisible or similar magics? The rules are silent on perceiving invisible objects as the rules all focus on seeing invisible creatures.

Do you treat them like hidden objects and allow a perception check?

Do you not allow it to be perceived unless someone walks into it (or uses magic to find it)?

Or did I miss a rule somewhere?

Perception checks relying on sight automatically fail. Perception based on other things may succeed, but you'd need an action declaration to tell what to do. The portal for a Rope Trick doesn't make sounds, but you might hear things in the rope trick, or smell them, thereby alerting you to something in the area. This will vary for whatever you have that's invisible and how it's being looked for.

 

[Oofta]

My rulings? Unless they have See Invisibility or similar, it's going to be difficult to find. Stumbling across it, noticing anything external that's odd.

So let's say there's an invisible statue. Maybe it's an inactive stone golem or similar but without something external to the statue it's not activated. You have to be able to sense it somehow. If it doesn't, smell, isn't giving off a different temperature, isn't making noise, you aren't touching it you probably don't know it's there. However, there could be thing external to the statue. The rest of the floor is covered in dust, cobwebs hang from it, a fly bouncing against it, a snowdrift, something. Maybe with a high enough perception, in the range of 30 or so, a person could notice weird echoes or subtle disturbances in the wind.

Doesn't come up often, but that's how I handle it. Basically you have to literally stumble across it in most cases.

 

[Lyxen]

Like most things about stealth and detection in the game, it's mostly within the DM's hands with a few guidelines, in particular the fact that invisible things cannot be seen without magic or a special sense, but are not hidden either in the sense that they are not imperceptible, so if again depends on the circumstances.

Does the source radiate something else like sound, smell, light, vibrations, etc? And is the environment providing lost of distractions (e.g. ambient noises or smells) or, on the other hand, providing clues (lots of dust in the air, cobwebs, etc.) ?

It's really up to you to see whether passive senses (probably perception) apply, with or without adv/dis depending on the circumstances.

Just remember that, by default, this is a dangerous world where people/creature who stay alive are on the lookout for danger, and don't discount sixth/danger senses from heroes and their adversaries.

It's not a rule and not more than a general ruling from a podcast, but JC said that a DM would not be wrong to rule that, in combat, people keep a general track of invisible creatures which are not hidden, in addition to the stress of the fight. Again, I don't apply this straight out of the box, I take circumstances into account, but it's just goes to show that invisible things are not necessarily completely invisible.

After that, you you apply things like the extraordinarily well done ability of the stalkers in Horizon Zero Dawn, where things are really almost impossible to perceive when motionless, but I think it detracts a bit from the fun of the game if PCs have really zero chance to spy the invisible scrying sensor from their enemy (and the other way around, actually).

 

[MarkB]

If something is invisible, and is not making sound or leaving tracks, it's generally undetectable except through happening to touch it.

If characters suspect there's something there to detect and feel around for it, that would be an intelligence (investigation) check.

See invisibility obviously works to detect such things, but detect magic might also reveal that there's an aura of illusion magic there.

 

[DEFCON 1]

For me, invisible objects occur infrequently enough that I take each instance on a case-by-case basis and don't bother with trying to establish one set of rules.

If an Arcane Eye is spying on the PCs, the reason for the enemy doing it and where/how/what the PCs are doing at that moment in time will help dictate whether there would be a reason for them to notice something might be amiss. So I'll make a ruling in the moment rather than trying to establish a system beforehand to try and cover it.

 

[jgsugden]

Thanks for the comments. I was just curious - I've had this come up specifically with Arcane Eye and Rope Trick a lot recently as we have PCs that use them a lot, now.

 

[Maxperson]

There are several things in D&D that are not creatures but are invisible... The portal of a Rope Trick. The Arcane eye's arcane eye.

As a DM, how do you determine if the PCs can perceive these things without the aid of see invisible or similar magics? The rules are silent on perceiving invisible objects as the rules all focus on seeing invisible creatures.

Do you treat them like hidden objects and allow a perception check?

Do you not allow it to be perceived unless someone walks into it (or uses magic to find it)?

Or did I miss a rule somewhere?

See invisibility says, "For the duration, you see invisible creatures and objects as if they were visible..." If it's invisible, I allow the spell to see it unless something explicity says the spell won't work.

 

[Stormonu]

Has anyone had to rule on whether detect magic can locate an invisible item?

I’ve personally ruled that the individual can “feel” something hidden is in range, but its location cannot be pinpointed.

 

[jgsugden]

Has anyone had to rule on whether detect magic can locate an invisible item?

I’ve personally ruled that the individual can “feel” something hidden is in range, but its location cannot be pinpointed.

That is correct RAW: Detect Magic does two primary things:

1.) You sense the presence of magic within 30 feet of you. The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt. If there is magic within 30', you tell the player that the PC senses magic unless it is blocked by one of the described barriers. As most PCs have magic items, this is almost always a yes after your first adventure or two - even a potion of healing gets you a yes.

2.) If you sense magic in this way, you can use your action to see a faint aura around any visible creature or object in the area that bears magic, and you learn its school of magic, if any. If they do not use an extra action, they do not get the extra info unless the creature or object is visible. An invisible creature or object, as well as one that is covered by anything at all, is not visible. As such, the spell will not provide an aura for it - but will give the binary determination that magic is present.