Interaction between perception and stealth in obscured conditions

Question

The rules for stealth in 5e are notoriously vague. I've been DMing 5e for about a year now, and there's something that's always bugged me about stealth in 5e. We've had several discussions about these issues in my group.

A quick summary of the rules: When someone is trying to hide, you compare their stealth check to the other party’s passive perception or a perception roll, based on the situation. You can normally only hide in lightly or heavily obscured places, depending on your feats and DM ruling. Out of combat, someone distracted could be stealthily approached in broad daylight, for example. Perception is the skill that allows you to notice things, not only through sight, but also through hearing, etc.

Which leads to my actual questions: using sight to perceive objects that are lightly or heavily obscured both imparts a penalty. You get disadvantage on perception checks that rely on sight for the former and you can’t use any skills that rely on sight for the latter, as you’re effectively blinded when looking into a heavily obscured area.

• Does this mean that if someone is hiding - since they need to hide in obscured environments - that the person trying to detect them always has disadvantage? If so, this means that stealth checks pretty much always succeed, as a -5 to passive perception is devastating. Or is there no disadvantage because searching for a hidden person does not solely rely on sight but relies on hearing as well?

• The PHB Errata state that the question isn’t whether a creature can see you when you’re hiding. The question is whether it can see you clearly. One of my players has argued that this means that you can approach an enemy in dim light out of combat after a successful stealth roll, even if that enemy is looking straight at you, and that this enemy even has disadvantage on his passive perception to spot the player (see question above). Is this truly in line with RAW ruling? Seems a bit strange, as anyone without darkvision should still see someone approaching pretty clearly in dim light.

Thanks in advance!

Answer 1

If someone is hiding, do detection attempts always have disadvantage?

This is a great question. From the rules, the answer appears to be 'No', but it isn't explicitly stated. I'm inferring it from this section of the basic rules for Hiding:

Passive Perception. When you hide, there’s a chance someone will notice you even if they aren’t searching. To determine whether such a creature notices you, the DM compares your Dexterity (Stealth) check with that creature’s passive Wisdom (Perception) score, which equals 10 + the creature’s Wisdom modifier, as well as any other bonuses or penalties. If the creature has advantage, add 5. For disadvantage, subtract 5.

For example, if a 1st-level character (with a proficiency bonus of +2) has a Wisdom of 15 (a +2 modifier) and proficiency in Perception, he or she has a passive Wisdom (Perception) of 14.

Emphasis mine. In this case, the rules are specifically explaining how to calculate the passive perception to detect a hidden creature. Since the rules for hidden dictate that the creature must necessarily be unable to be seen clearly (implying light or heavy obscurement), we can infer that this hidden creature is in some way obscured from the searcher. However, since the passive perception total listed is 14, and does not in any way reference a -5 modifier for an obscured creature, it seems like we can be reasonably sure that detecting hidden creatures happens outside the influence of obscurement. Otherwise, the math present would necessarily have to include a -5 for detecting an obscured creature.

Can you sneak up on someone in dim light according to RAW?

This one is DM dependent according to the rules. We can piece this together from the examples that the basic rules give us:

In combat, most creatures stay alert for signs of danger all around, so if you come out of hiding and approach a creature, it usually sees you.

This gives rules for when a creature can detect a hidden creature approaching it. However, since it specifically calls out 'in combat', and since 'out of combat' is not addressed, we have to assume that being out of combat doesn't change the core ruling of the 'hidden' effect (otherwise it would also have a callout, because specific beats general).

The generic hiding rules that necessarily must apply out of combat are:

You can’t hide from a creature that can see you, and if you make noise (such as shouting a warning or knocking over a vase), you give away your position.

and the errata:

The DM decides when circumstances are appropriate for hiding. Also, the question isn’t whether a creature can see you when you’re hiding. The question is whether it can see you clearly.

So in this case, the game is deferring to the DM. You are well within RAW to tell the player that they can't approach the character in dim light from the front and remain hidden. This is even more overt than a simple rule-0, because the published rules specifically call out the DM's ability to overrule it.

My reading of the published rules appear to default to allowing that, but they also give the huge caveat that the DM can overrule it. However, with what we found out above, the detecting creature would NOT receive a -5 penalty by default (unless conditions occurred to warrant disadvantage on the check(s)).

Answer 2

Not Necessarily

The rules for hiding and Lightly Obscured/Heavily Obscured cover Perception checks that rely on SIGHT (PHB 184). However, hiding isn't just about seeing someone, but also hearing them.

Rulings may differ by DM, but it seems that by RAW there would not be disadvantage or blindness on a perception for hiding in light/heavily obscured environments as sound is still a viable factor.

Answer 3

The issue is you're conflating Sneaking and Hiding - they're two different uses of the skill. Mechanically speaking:

• Sneaking is moving to someone (or away or around) who has not yet spotted you in hopes of not being spotted.
• Hiding is moving behind some obscuring material after having been spotted.

Sneaking is almost impossible once combat is past the surprise round. Note that, if everyone is stealthy during the surprise round, the GM is quite right to allow a second surprise round — this is just holding an ambush one more round — but also to call for fresh stealth rolls. This can be a VERY tense GM technique, and while not explicit in the rules, it's use is suggested in Horde of the Dragon Queen, chapter 3.

For sneaking, any intervening obscurement logically applies.

For Hiding, however, we get into the ugly issue. You have to have obscurement to try it. But not all obscurement is area effect. A little logic, and remembering that the cover being entered isn't entered yet when the roll to hide is made helps me visualize it.

For example, Big Bad is at point A; Sandy the Sneak is at B. Next to Sandy is a hedgerow, and nothing is between A & B, and it's a bright day. Big Bad is likely to see her enter the bush, and keep a mental note, and watch where she goes once she's behind the bush. Big Bad should not have reduced perception, because he can clearly see her enter the concealment. Big Bad still knows she's around there even if she makes the hide roll. He can still drop a fireball on her.

Now, add fog. 20' of good fog should be enough to hide her entry. Big Bad can't clearly see her, so when she hides, yes, Big Bad uses disadvantaged Passive Perception. Once she's hidden, his Passive Per should take penalties on her attempts to stealth towards or away from him... but not her entry into hiding.

For Surprise it's any obscurement helps - possibly for both sides! two sneaky parties can in fact surprise each other. (Both were sneaking, both rolled higher than the other's Passive Perception.) A double surprise isn't really all that interesting - it's just that everyone has a reaction available from the start of actual fighting.

Answer 4

Perception is based on Intelligence, not just eyesight.

Some games have "Sight" as a characteristic. In such a game it might make sense that all such rolls faced a penalty based on obscuring factors. But DnD is not such a game. "Perception" is based on Intelligence, and represents not just the character's eyesight, or even just his hearing, olfactory senses, and touch, but his smarts. In English, to be "perceptive" means to be able to understand more than just what the ordinary senses tell you. In the DnD game, Perception means the ability to anticipate as well as simply sense.

Given this, let's analyze your player's contention that he can sneak up to someone in dim light. The dim light covers one sense - sight - but is irrelevant to hearing and smell. Moreover, it is countered by the fact that, in dim light, the target will likely be paying more attention to his environment. The concept of "hiding in plain sight" works both ways, after all. As a DM I have often ruled that a character has hidden in such a predictable way that the target receives Advantage (or conversely, the character has Disadvantage). Of course, you should also allow the character Advantage if he hides in a creative way.

The subject is too broad to be addressed in just one post, but to summarize, you should evaluate the question of Advantage/Disadvantage based on not just sight, but sound (and sometimes, smell or feel) and intelligence. If the tactic seems too dumb to work, apply Disadvantage as you see fit.