I’ve found the rules for Stealth in the new edition of Dungeons & Dragons rather hard to follow. It doesn’t help that I haven’t seen the Player’s Handbook yet, but it seems that it basically just is the rules from the Basic D&D game, so there is little further clarity there. I rather hope Stealth gets a section in the Dungeon Master’s Guide!
It doesn’t help that there are some usage of terms I didn’t expect. The lightfoot halfling says “You can attempt to hide even when you are obscured only by a creature that is at least one size larger than you.” Based on how the terminology worked in previous editions I would have thought that was “you have cover” rather than “you are obscured”, so I’m also trying to grasp the slightly different way they have of phrasing things.
In any case, here’s an explanation of how Stealth and Hiding work in 5E, per the rules that we’ve been given.
You may Hide only when opponents can’t see you (clearly).
This comes from Chapter 7 of the Basic Rules (Using Ability Scores, sidebar Hiding). In general, this means that you must have a lot of cover or be Heavily Obscured. Note that some characters, like the lightfoot halfling, have abilities that make it easier to hide.
It takes an action to Hide (Chapter 9: Combat), although some characters (like Rogues) can do so as a bonus action.
You make a Hide check by making a Dexterity (Stealth) check which is opposed by the Passive Perception of the opponents. You need to roll higher than their Passive Perception, as a tie indicates the situation remains the same as before the check. (Chapter 7: Using Ability Scores, Ability Checks, Contests)
Once hidden, you may move slowly and still not be seen, as long as you aren’t in the open.
There’s a couple of rules coming into play here. The first is from Chapter 8: Adventuring (Activity While Travelling), which states that a party can move at a slow pace and try to surprise or sneak past opponents as long as they’re not in the open. I interpret this as a character moving at two-thirds of normal speed whilst behind some form of cover or if obscured in any way. (Moving at half-speed was typical in 3E and 4E; alternatively the DM might use no penalty at all).
Meanwhile, the section on Hiding in Chapter 7: Using Ability Scores indicates that in combat, you’ll usually be seen if you approach a creature, but the DM may rule that if it’s distracted you can remain hidden. I believe this is a rule that modifies the rule for being in the open – you can remain hidden as long as you have cover or obscurement, but if you approach it in the open, you can remain hidden if it’s distracted (thus, looking the other way).
You gain Advantage when you attack when hidden
This is from “Unseen Attackers and Targets” in Chapter 9: Combat. This may also enable a thief’s sneak attack.
You lose your hidden status once you attack
This is also spelt out in the “Unseen Attackers and Targets” section. You actually give away your location when the attack hits or misses, so you’ll still have advantage on the attack – it’s only after the attack resolves that you lose your hidden status. (So your attack can’t be interrupted by someone readying an action; although they could attack you before you move or hide again).
Characters attacking you when you’re hidden have Disadvantage
Not only that, but if someone can’t see you or hear you, they have to nominate where they’re attacking – if they attack the wrong location, they automatically miss (and probably don’t even discover you’re not there!)
It’s possible to be invisible (or totally concealed) but not hidden – in this case, the opponent knows what your location is. If you’re hidden, the opponents don’t know where you are.
I would rule that if an attack hits you when you’re hidden, you lose the hidden status – the opponents have worked out where you are!
You can spend an action to Search for hidden opponents
This is one of the Actions in Combat (Chapter 9: Combat). The DM will choose whether a Wisdom (Perception) or Intelligence (Investigation) check is required. The roll needs to beat the Dexterity (Stealth) check made by the opponent when they first became hidden. As before, a tie means that the check failed and the opponent remained hidden. If there are several hidden opponents, I’d say one check could find them all.
I would also say that if successful, you could alert your friends to the hidden character’s location; thus they lose their hidden status against your allies as well.
Note also that if you’re trying to find someone using sight in a lightly obscured area, you have disadvantage on Wisdom (Perception) checks, and automatically fail those checks in heavily obscured areas! Normally, you’d use your hearing to locate the target instead, so this rule wouldn’t apply, but against totally soundless creatures like ghosts, the DM may use the penalty.
What Hidden actually means and the difference from Invisible
Being Hidden means opponents do not know your location or perhaps even that you’re there. You have advantage on attacks against them, and they have disadvantage on attacks against you, and they even need to nominate where they think you are… if you get it wrong, they fail automatically!
When you are Invisible, opponents do know your location (although you can spend an action to Hide and become Hidden), so they can attack you – albeit with disadvantage.
The chief bonus of being Invisible is that when hidden you can move in the open without opponents seeing you, although you’ll still lose your hidden status if you make noise or attack.
In the first round of combat, individual combatants are surprised if they failed to see any of the opposing side. This requires all the opponents to be hidden and their Dexterity (Stealth) checks to beat the Passive Perception of the combatant. If a combatant spots even one opponent, they are not surprised.
Surprise means a combatant can’t move or take actions during their first turn of the combat, nor may they take reactions until that turn ends. (See Chapter 9: Combat: Surprise).
Note that you have to be hidden (or hidden and moving stealthily) to surprise opponents – which means your speed will be lower than usual. Everyone in the group must make Stealth checks, which are opposed by the Passive Perceptions of the opponents.
You also gain the benefits of being hidden on your initial attack, unless you have to move and stop being hidden before attacking – so moving in the open or moving at a normal speed or faster.
The DM’s Judgement also applies
All of these rules and suggestions are subject to the DM’s adjudication. The glory of D&D is that it is a game with a Dungeon Master, and there are times when the DM can decide an exception to the basic rules applies; this seems particularly applicable to the Stealth rules.
Well, that’s what I’ve been able to tease out of the Basic Rules on Stealth, Hiding and Surprise. Let me know if I’ve missed anything! I hope you find the summary useful.