Hi

Our group keeps arguing how invisibility and hidden works. Can you always attack an invisible creature or do you have to guess to square? Is your location concealed when you are hidden or in darkness? What about invisible? Some say you have to guess the squares always. I have this vague thing about stealth preventing sound and you could attack using noise?

Im a little lost. Help our playgroup please.

Oh boy, here we go again

Invisible

Hiding

You can attack invisible creatures unless they are also hidden. I wouldn't allow you to use features that require you to "see" the target ie. some spells. An invisible creature can always take "hide" - action. On the other hand, I generally hide hidden enemies from the map until someone either spots them with perception roll or a spell, or they are revealed due to them attacking/casting a spell.
On the same way I wouldn't hide the location in darkness unless a player/enemy takes "hide" - action and succeeds on dc 15 stealth check.

Invisibility is just a condition. You can read the effects of it as a condition and that is the full extent of being invisible. The idea is that even though you’re invisible, you can still be heard, smelt, and maybe even noticed (ie through puddle splashes or footprints). If you want to be more hidden, you can hide. To hide you take the Hide Action and make a stealth check while “unseen”. This means you must be either invisible or behind Full Cover (like a wall or something). While hidden, you are untargetable, creatures are unaware of your location, and they must take the Search action to find you. So Invisibility basically just allows you to hide in the open, amongst its other listed benefits.

I lean towards the "guess at squares" method, however for both hidden and invisible enemies you can make a perception check vs their stealth check to try to "see" them via things like footprints or noise every turn. I'd always give advantage to an invisible or heavily obscured enemy for this contest, and for an enemy who is both invisible and heavily obscured I probably wouldn't even let a roll happen. Vice versa for an enemy in the open in broad daylight.

If you can't see an enemy, treat it as if you are blinded for attacks against them. No ranged attacks (if you wanna guess at a square that's fine but it's still disadvantage) and melee attacks at disadvantage (just swinging wildly in all directions). Enemy attacks are also at advantage.

As always, DM gets to decide when hiding is possible or not, and what advantages/disadvantages are present.

You're going to get a lot of answers saying invisible creature locations are always known. I think its definitely true that invisible creatures should be presumptively making enough noise that you can hear them, the rules support that and it's mostly the more fun way to play. That said, I think "[t]he creature’s location can be detected by any noise it makes or any tracks it leaves" leaves a DM plenty of discretion to say that some creatures won't make detectable noise, based on some combination of the creature's nature and the environment (floor material/ambient noise). Also think a strong case can be made that an invisible creature who isn't moving around will not be automatically known even if they're not actively hiding.

All the invisible condition says is creatures have disadvantage on attacks. That's it. You can think of the disadvantage as your character 'guessing which square' the monster is at.

There is no such thing as a hidden condition in 5.5e. Successfully using the hide action results in the invisible condition (they can't be seen).

I think it's pretty widely accepted that these rules are fairly unintuitive and iincomplete. I haven't seen a better version that most people agree with.

When I DM, this is my personal way to run it. This is not RAW but it keeps things running smoothly for my table.
- Turning invisible applies the invisible condition, but I dont remove the token from the battlefield
- An invisible creature or one behind cover/fog cloud can then take the hide action and if successful I will remove the token. I use this exceedingly rarely as it is really frustrating for players. I also try to avoid monsters that can turn invisible and hide in the same turn unless it is a restricted number of times per day.

To me this makes it so it's really hard to not know where you are as you need have a way to get cover/become invisible, use actions economy to hide, and have a way to maintain that cover while moving around the map.

I'll add to this since it's best to just read the rules, but I'll explain them a little here too.

If you are hidden, you don't know where something is.

Invisible means that you cannot see them.

An invisible creature that is not hidden is a creature you know where it is. A hidden creature is also invisible.

So, if a creature is hidden, you don't know where it is, thus you must guess its location.

An invisible creature you do know where it is, so you can just attack it despite not being able to see it.

Worth noting that these are links to 5e definitions. 5.5e introduces all sort of interpretation arguments, since the Hide action now gives you the Invisible condition. Functionally the same effects, but semantically ambiguous enough for many a reddit thread lol

It's perception with disadvantage to locate an invisible creature. Only exception is when there are clues to work off (ie. orc sees invisible PC by following footsteps on snow, here I'd make a regular perception or no roll), or it's location has been found and called out by others (no perception needed) and it hasn't moved.

Hide requires a stealth roll vs passive perception, but you don't disappear. It is still possible for a creature to find you if it changes position (ie. walks behind the wall you're at) or if it uses its action to find you (perception vs the result of a stealth roll). Because you're using passive perception, there are varying levels of success. It's easier to hide from a wolf than a dragon, for example.

Both give advantage on attacks made by the hidden/invisible creature. Both would require guessing squares if no location has been determined, and regardless of whether they are there or not you should make them roll for it at disadvantage. Do not calculate cover on AC unless it's relevant (ie. hiding behind bush).

Darkness could conceal creatures, but they also conceal your PCs. Regardless, most parties and many creatures have darkvision, so the efficacy of this beyond magical darkness is mixed. Blindvision helps, but comes with its own limitations. Noise can reveal location, yes, and stealth should prevent that if rolled well.

As always, you're free to modify any of this if you feel the mechanics are too light or punishing. But get a feel for it RAW first and adapt based on your play experience.

Another thing to note as people get it wrong all the time. Being invisible doesn’t give you advantage on your stealth checks. I see so often DMs will grant advantage for hiding while invisible.

Technically there’s no advantage for the invisible hider or disadvantage for the searcher. Being invisible grants heavily obscured status. Meaning all perception checks to see the individual auto fail. However, as noted in the condition for both hiding and invisible, a creature can still make a perception check to find them based on sounds made or tracks left. And there’s no disadv for that.

However, as I mentioned above, a lot of DMs rule advantage on stealth while invisible or give disadv on the perception check.

For me it’s obvious that when something is hiding you remove its token. I will allow a stealth check to move while hidden provided you stay lightly obscured from your foes the whole time and this makes any attacks on the square you were at automatically miss. Someone needs to use Thai action to actively look for you perception and look near the right place to find you (or hopefully move in such a way that you are no longer lightly obscured from them revealing you automatically.

Anyone attacking that doesn’t have the skulker feat reveals the square they were on when they attacked.

I tend to find that if the location isn't known it can be really frustrating for my players. It is also asymmetric for a non-careful DM as the DM always knows locations and has to pretend they don't.

There aren't a lot of good ways to find creatues and not waste a turn*. Using a perception check is generally an action, so you can't do anything afterwards and typically the monster just can hide again before your next turn anyways. Your allies may also not benefit from the perception check, depending on how you rule, so it may require actions from every single character.

*Yes, I know there are spells and blindsight. Many spells still require an action and can still be often wasted if you don't know position (e.g. faerie fire). If my party had action-economy friendly anti-invisibility features, I'd be more likely to run a invisible/hidden monster without position known in order to highlight those abilities. I'm just cautious of the tremendously frustrating fights when a party doesn't have these features, the features don't work, or if the features are to costly in terms of action economy for what they do.

These are the 2014 rules.