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When we run skill contests, especially Stealth contested by Perception, we sometimes struggle to work out whether to apply advantage to one skill or disadvantage to the other. It matters for two reasons:

  • multiple advantages and disadvantages don't stack for any single skill check
  • advantage and disadvantage cancel each other out

An example may serve to illustrate:


Example

The dwarven fighter became separated from the rest of the party and was stuck in a long dark tunnel with three human cultists bearing down on her; they were carrying lights but she was still in darkness. She made a Stealth check to hide from them because she wanted to shoot at them with advantage. Here's how I ruled advantage and disadvantage would stack up on the respective Stealth and Perception checks:

  • The fighter's Stealth check had advantage owing to being heavily obscured in the darkness
  • The fighter's Stealth check had advantage due to her boots of elvenkind
  • The fighter's Stealth check had disadvantage due to her armour
  • The fighter made a standard Stealth check because the advantage and disadvantage cancelled out; the second advantage did not come into play
  • The cultists' Perception check had advantage because they had already been attacked by the fighter, they knew she was hiding in the darkness up ahead of them, and they expected further attacks to come from that direction.
  • The net result was that a standard Stealth check was contested by an advantaged Perception check.

Reviewing the PHB rules on Light and Vision afterwards, I realised I should have made the heavy obscurement into a disadvantage for the cultists. That would have changed the skill contest as follows:

  • The advantage to the fighter's Stealth check granted by being heavily obscured would have become a disadvantage to the cultists' Perception check.
  • The fighter would still have made a standard Stealth check because she would still have had advantage and disadvantage, which would cancel out
  • The cultists' Perception check would have had disadvantage because the fighter was heavily obscured from them
  • The cultists would now have made a standard Perception check because their existing advantage would have been cancelled out by the new source of disadvantage
  • The net result would then have been: a standard Stealth check was contested by a standard Perception check.

I'd given the cultists an unwarranted leg-up.


So the question is, for the factors that affect the Stealth vs Perception skill contest, which do you apply to the Stealth check, and which do you apply to the Perception check?

Your reply should address some or all of the following factors, saying which check each applies to, and why:

  • movement of the stealthing or perceiving creature
  • obscurement
  • cover
  • camouflage
  • attention or distraction of perceiving creature
  • ambient light, noise or smell
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  • 2
    \$\begingroup\$ OK, so I realise that my question conflates two things: • An observation that there are consequences to applying advantage and disadvantage to contested skill checks that may not be immediately apparent, to the extent that advantage and disadvantage can stack depending on which skill check they're applied to. • An exploration of how to apply factors that grant advantage or disadvantage to the two skill checks in a Stealth vs Perception contest: specifically determining which skill a particular factor applies to. I'm sorry to respondents for not being clearer about this. I'll clarify. \$\endgroup\$ – Clearly Toughpick Jan 18 '17 at 8:15
  • \$\begingroup\$ I upvoted this question for two reasons: (1) that you took the trouble to examine in detail what had gone on mechanically during that encounter, and (2) because your problem statement gave me enough to understand the question thoroughly. \$\endgroup\$ – KorvinStarmast Aug 10 '17 at 13:31
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This is not something that has a definitively right or wrong answer, however, the choice does have mechanical effects. Because disadvantage cancels any number of advantages (and vice-versa) piling them all on one roll or the other gives a different outcome than if you split them between the rolls.

For your example, the second is more right than the first but only because dim light specifically imposes disadvantage to Perception checks as it is a "lightly obscured" area (PHB p.183).

In general, when considering advantage/disadvantage situations consider who is advantaged or disadvantaged - the effect should apply to their roll or passive check.

For the situations in your example, this is how I think about it (which does not mean it is right or the way you or anyone else should think about it):

  • Being heavily obscured - being unable to be seen (or seen clearly) is a prerequisite to hiding and provides neither advantage nor disadvantage to Stealth. It does, however, provide disadvantage on Perception (both lightly and heavily obscured do this)

  • Boots of Elvenkind - gives advantage to Stealth because they say they do

  • Heavy armor - gives disadvantage to Stealth because they say they do

  • Knowledge of the Fighter's presence - to me, this doesn't suggest advantage: I've played hide and seek and knowing that there are people out there to find doesn't really make it easier to find them. Knowing he is there allows the pursuers to spend an action to make an active Perception check rather than relying on their passive Perception - you get passive Perception for free but active Perception costs you. Remember, succeeding on a Perception check means you know exactly where the person is: it doesn't necessarily mean you can see them - you may have located them be smell, or hearing, or touch, or (in truly exception circumstances) taste - Invisible creatures can be Perceived!

    As an aside, if they are using their action to Dash rather than Search, this may warrant disadvantage on their passive Perception (and they can't make an active check) as they are hurrying by too swiftly to take proper stock of their surroundings. This gives pursuers a nice dilemma - if their quarry is hiding they want to go slower and look for them but if their quarry is running then they want to run too - you pay your money and you take your chances.

For me this gives a Stealth check with advantage cancelling disadvantage and a Perception check with disadvantage: either -5 on a passive check or roll twice take lowest on an active check and they only get their active check if they spend an action to Search.

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    \$\begingroup\$ "It does, however, provide disadvantage on Perception (both lightly and heavily obscured do this)" - technically, being heavily obscured means "A creature effectively suffers from the blinded condition when trying to see something in that area." And the blinded condition says: "A blinded creature can't see and automatically fails any ability check that requires sight." So rather than disadvantage, you fail any Perception check related to sight automatically if you try to see into a heavily obscured area. \$\endgroup\$ – V2Blast Dec 1 '18 at 0:54
  • \$\begingroup\$ @V2Blast detecting a creature in the dark doesn’t “require sight” - it requires hearing, scent and touch. Particularly touch, I’m really good at finding the corner of my bed with my toes, after which anyone who can hear can find me. \$\endgroup\$ – Dale M Dec 1 '18 at 4:47
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    \$\begingroup\$ By that logic, though, visual obscuration then has no effect on Perception checks made to find creatures via non-visual means. "Lightly obscured" only imposes disadvantage on Perception checks that rely on sight. \$\endgroup\$ – V2Blast Dec 1 '18 at 5:28
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Having given this some thought, and after reviewing the other answers, here's my take.

When advantage and disadvantage might apply to Stealth checks

  • movement by a hiding creature - keeping still might grant advantage on its Stealth check, moving slowly might have no effect, moving at normal speed or faster might impose disadvantage.
  • camouflage - normally grants advantage if it matches the environment.
  • being inherently conspicuous - giving off or bearing light, or being or wearing something noisy will impose disadvantage or preclude you from being stealthy. Consider a cat wearing a bell, a cleric in full plate, or a commoner lighting her way with a candle.

When advantage and disadvantage might apply to Perception checks

  • obscurement and cover from the perceiving creature - separately or in combination these may impose disadvantage, possibly with extra penalties. They apply to Perception checks because they are always relative to the perceiving creature, for example a rogue in an area of dim light is lightly obscured from a human but not from a dwarf, owing to the dwarf's darkvision.
  • movement of the perceiving creature - consider whether being still or moving fast affect Perception checks with advantage and disadvantage respectively.
  • physical impediments to perception can affect senses such as hearing and smell. Consider the difference between a PC hiding behind a large cabinet with full cover, or standing in the next room on the other side of a closed door: one will be easier for a wolf to sniff out than the other. Watching or listening to a conversation is easier when you are in the same room rather than having to press your eye or ear to the keyhole of a door. Some sorts of obscurement might also acts as physical impediments, such as how dense fog, thick vegetation and heavily falling snow can all mute sound and smell.
  • attention and distraction might grant advantage or impose disadvantage respectively. An example of attention is seeing a goblin hide behind a tree, such that you are pretty certain you know where the goblin is. You are attending to the goblin's position, which makes it easier to find it again. This usage has been set out by both Jeremy Crawford and Mike Mearls.

This discussion has crept beyond the original scope of the contest between Stealth and Perception - what with watching conversations through doors, and all - but I think the factors set out here still apply to these skills in isolation, as well as in contest.

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It seems like you answered your own question. I could see resolving this in one of two ways.

Be more familiar with the rules

I'm not trying to sound rude, but all it came down to was that there were rules that you didn't remember. If it's important to you, possibly make a cheat sheet especially for Perception/Stealth to keep with you.

Roll all Perception/Stealth contests without Advantage/Disadvantage

(unless either side has a clear, uninhibited advantage/disadvantage.)

Each side of a contested roll is likely to have its own advantage(s) and disadvantage(s). However, there is a rule

If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage.

Therefore, if you are ever in a situation where you are going through multiples, you could summarize it as saying both sides of both and therefore roll a single d20.

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  • \$\begingroup\$ I'm downvoting this answer because it's too simplistic. In contested skill checks, advantage and disadvantage actually can stack depending on whether you decide a given factor should give advantage to one side or disadvantage to another. In my example, switching heavy obscurement from advantage on one side to disadvantage on the other changed the way they stack. \$\endgroup\$ – Clearly Toughpick Jan 18 '17 at 7:58
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    \$\begingroup\$ I was referring to "If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage. " dandwiki.com/wiki/5e_SRD:Advantage_and_Disadvantage (3rd paragraph) \$\endgroup\$ – Ifusaso Jan 18 '17 at 12:48
  • \$\begingroup\$ My argument is that in a complex perception situation, there are SO MANY ways to cause advantage and disadvantage that you it would not be unfounded to assume that there is at least one of each. That being said, that was my backup answer. There's still the idea that a cheat sheet could help in the future because all the 'normal' modifiers are going to be by the rules that you've already found. \$\endgroup\$ – Ifusaso Jan 18 '17 at 12:50
  • \$\begingroup\$ I'm going to edit my answer to include that line as its center point. \$\endgroup\$ – Ifusaso Jan 18 '17 at 12:53
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    \$\begingroup\$ It's true that I gave the example of how obscurement applies to Perception (and not Stealth) from the book, but I was keen to consider how other factors might affect the Perception vs Stealth contest. And it's legitimate to answer my own question: if I've wondered about it, then others may have too. \$\endgroup\$ – Clearly Toughpick Jan 21 '17 at 16:47
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In this specific case (perception against stealth) I would employ a very simple distinction: Anything advantage/disadvantage that would also apply to someone spotting a hidden object (stashed loot, secret door etc.) should go to perception. Anything that I would instead use to determine DC under those circumstances goes to stealth.

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