Can you roll perception against invisibility?

[Xavier319]

I'm sure this has been discussed, but my search has not answered the question I have. Many seem to accept that everyone gets an automatic perception checks against invisible targets. IF that's RAW, I'm fine with it, but what bothers me is the word "invisible". It means, by definition NOT visible.

Now, RAW question is this. The invisibility spells states the following...

"Of course, the subject is not magically silenced, and certain other conditions can render the recipient detectable (such as swimming in water or stepping in a puddle). If a check is required, a stationary invisible creature has a +40 bonus on its Stealth checks. This bonus is reduced to +20 if the creature is moving. "

It says other conditions can render the recipient detectable, indicating that in the absence of those things (stepping in a puddle, swimming, pushing a curtain aside to walk into a room) you are NOT detectable by sight via the perception skill. As in, you would not even get a skill check to SEE the INvisible creature.

I ask as a GM, not as a player, so no power gaming intended so please keep knee-jerk reactions to yourself. I am curious about actual rules. If someone is invisible, walks into a room, does the guard get a perception check? It doesn't matter if he CAN make the check, does he GET one? My contention is that barring any details that would give the guard some way to notice the invisible creature visibly, he would not. Sound is a completely different question.

What is the RAW here?

[AaronUnicorn]

Since Pathfinder doesn't single out "Listen" vs "Spot", sound isn't really a completely different question, so, yes, the guard should get a Perception check when dealing with an Invisible opponent.

Of course, with a +40 to the invisible character's Stealth check (or +20 while moving), that check doesn't have a snowball's chance in Hades of succeeding, and as a GM, I wouldn't bother rolling it.

But yeah, a Perception check includes information from all the senses, so even if you can't see someone, you still have a chance to notice that they're there.

[toastedamphibian]

Now the absurdity of the size of that bonus is another can of worms completly. When detecting someone on the other side of a brick wall is easier than detecting someone breathing on your neck, your rules are daft. No idea why the rules for invisibility are not "you gain total concealment".

[RumpinRufus]

Xavier319 wrote:

If someone is invisible, walks into a room, does the guard get a perception check? It doesn't matter if he CAN make the check, does he GET one? My contention is that barring any details that would give the guard some way to notice the invisible creature visibly, he would not. Sound is a completely different question.

I don't think I understand the question. Is the guard deaf? If the guard is deaf and the invisible creature is walking on a clean stone surface, I could see the argument that the guard does not get any check. But if either the guard is not deaf, or if the surface is at all dusty or pliable (like wood, rug, etc.) then the guard gets a check.

[thejeff]

Also note this from the Invisibility Special Ability rules: A creature can generally notice the presence of an active invisible creature within 30 feet with a DC 20 Perception check.

It's hotly debated, but a common interpretation is that you always get a flat DC 20 check to notice something invisible is moving nearby. The Stealth +20 is needed to locate the creature's square.

[Xavier319]

RumpinRufus wrote:

Xavier319 wrote:

If someone is invisible, walks into a room, does the guard get a perception check? It doesn't matter if he CAN make the check, does he GET one? My contention is that barring any details that would give the guard some way to notice the invisible creature visibly, he would not. Sound is a completely different question.

I don't think I understand the question. Is the guard deaf? If the guard is deaf and the invisible creature is walking on a clean stone surface, I could see the argument that the guard does not get any check. But if either the guard is not deaf, or if the surface is at all dusty or pliable (like wood, rug, etc.) then the guard gets a check.

I was talking about JUST visibility. Nothing else. As I stated in my original post. Thanks or the input though! :)

Hmm flat DC 20 to detect something invisible is within 30 feet? That seems asinine. But if it's RAW it's RAW. They would still take penalties for things like being distracted, bad conditions, etc, but not distance. And it only says "something invisible is within 30 feet". curious.

[Pizza Lord]

You can roll Perception against an invisible creature, but there must be something you can reasonably notice. While Perception is Listen, Spot, and smell all rolled into one (even touch if you were trying to determine something in the dark with your fingertips) the game does differentiate between them. For instance, being deafened makes you fail all Perception checks based on sound, you would still get one to see a creature running across a hallway, but if you were specifically looking away or blindfolded or had no way to otherwise perceive it except by footsteps you wouldn't even get a check (or you would but it would be an automatic failure, which is semantic.)

If the invisible creature is silent or unable to be heard (from the observer's standpoint) you don't have to bother with Perception checks if they're cackling madly and clapping their hands. Similarly, if they can't be seen, it doesn't matter how much they're waving they're arms around... unless it's making something that's noticeable occur, like a breeze on the observer's face, or causing dust to fly about, or cobwebs to move. Even then you only get a vague sense of location.

Quote:

I ask as a GM, not as a player, so no power gaming intended so please keep knee-jerk reactions to yourself. I am curious about actual rules. If someone is invisible, walks into a room, does the guard get a perception check? It doesn't matter if he CAN make the check, does he GET one? My contention is that barring any details that would give the guard some way to notice the invisible creature visibly, he would not. Sound is a completely different question.

Assuming a normally perceptive guard, yes. technically he gets a Perception check for an invisible intruder entering the room. This represents hearing a footstep, a breath, the rustle of clothing. Even aside from sound, it could just be a change in air pressure, the electromagnetic field, the smell of aftershave or body odor, etc. Maybe even just the sensation of being watched (which could be anything from paranoia to scrying to guilt for slacking off on guard duty). As a GM, just be reasonable. In this case... a guard with no reason to suspect anything is likely taking 10, so they will not have a reasonable chance to notice anything amiss unless it's so obviously out of place as to call attention to itself (opening a door, breathing on the guard, being close enough that a creature without scent can literally identify your smell).

[Fafnoir]

thejeff wrote:

Also note this from the Invisibility Special Ability rules: A creature can generally notice the presence of an active invisible creature within 30 feet with a DC 20 Perception check.

It's hotly debated, but a common interpretation is that you always get a flat DC 20 check to notice something invisible is moving nearby. The Stealth +20 is needed to locate the creature's square.

I feel like this is misleading, I don't think the DC would be 20 in a majority of in-game situations (edit to clarify: as that DC seems to apply only to creatures not using stealth, and without any modifiers). By the numbers from the Invisibility special rules, I believe it should be:

Perception vs.

Invisible Creature, w/o Stealth, within 30':

• DC = 20 to notice presence, 40 to pinpoint square.
  Invisible Creature, w/ Stealth:
  
• DC = Creature's Stealth Roll + 20 to notice presence, Stealth Roll + 40 to pinpoint square.
  

It seems like the DC 20 perception check within 30' may likely come from the base DC 0 perception check to notice a visible creature, plus 20 from being invisible.

In both cases, the DC is modified as given in the table on the Invisibility entry:

• In combat or speaking: -20
  
• Moving at half speed: -5
  
• Moving at full speed: -10
  
• Running or charging: -20
  
• Not moving: +20
  
• Using Stealth: Stealth check +20
  
• Some distance away: +1 per 10 feet
  
• Behind an obstacle (door): +5
  
• Behind an obstacle (stone wall): +15

Given these numbers, if Tim the Rogue has a +12 to Stealth, is invisible, and is moving at half speed through a room with a guard 40' away,

DC = His Roll + 12 (Stealth) + 20 (Invisibility) - 5 (Moving Half Speed) + 4 (Distance)
DC = Roll + 31

An invisible stalker is in combat, so its stealth cannot be used. It is 20' away.

DC = 20 (Base) - 20 (In Combat) + 2 (Distance)
DC = 2

Both DCs are 20 higher to pinpoint the exact square.

However, to get back to the original question. The perception check is automatic in either case. Someone else mentioned it, but it's a result of bundling all the perception-type skills into one skill. The creature in question is invisible, which is taken into account by the +20 bonus to its stealth in the opposed check.

Source: Invisibility, per PFSRD.

[thejeff]

Fafnoir wrote:

thejeff wrote:

Also note this from the Invisibility Special Ability rules: A creature can generally notice the presence of an active invisible creature within 30 feet with a DC 20 Perception check.

It's hotly debated, but a common interpretation is that you always get a flat DC 20 check to notice something invisible is moving nearby. The Stealth +20 is needed to locate the creature's square.

I feel like this is misleading, I don't think the DC would be 20 in a majority of in-game situations (edit to clarify: as that DC seems to apply only to creatures not using stealth, and without any modifiers). By the numbers from the Invisibility special rules, I believe it should be:

As I said, hotly debated. I could defend either, but the flat 20 for notice is a common interpretation. (Edit: As is some variant of yours.) There's very little in all the rules surrounding stealth/perception/invisibility that's clearly agreed on.

[Xavier319]

Except that it specifically says the flat 20 is there and is modified by the following chart. and ON that chart is "stealth +20". So that means the flat 20 is if they aren't sneaking (aka big bob in his full plate). Seems cut and dry to me.

[Perfect Tommy]

It is flatly deceptive to say that its a flat DC20 to notice an invisible character when the words continue....

"There are a number of modifiers that can be applied to this DC if the invisible creature is moving or engaged in a noisy activity.

Invisible creature is… Perception
DC Modifier
In combat or speaking –20
Moving at half speed –5
Moving at full speed –10
Running or charging –20
Not moving +20
Using Stealth Stealth check +20
Some distance away +1 per 10 feet
Behind an obstacle (door) +5
Behind an obstacle (stone wall) +15"