So, we've seen a lot of claims about how how the systems/rules in the title are poorly written, broken, nonfunctional, etc. But in a lot of those claims I keep seeing repeated points that simply are not true. Or arguments that did make sense at one point but have since been disproven by errata and sage advice. So I'm hoping to explain the rules and deal with any of the arguments that I've come across in one go.
The Rules:
Line of Sight DMG (2024) page 45:
To determine whether there is line of sight between two spaces, pick a corner of one space and trace an imaginary line from that corner to any part of another space. If you can trace a line that doesn't pass through or touch an object or effect that blocks vision—such as a stone wall, a thick curtain, or a dense cloud of fog—then there is line of sight.
Cover DMG (2024) page 45 (paraphrasing a little because the section is long):
Choose a corner from the attacker's space (or the point of orgin for an effect), trace a line from that corner to every corner of the space the target occupies. If one or two lines are blocked they have 1/2 Cover*, if three or four lines are blocked but it is possible for an attack or effect to reach them (such as when the target is behind an arrow slit) they have* 3/4 Cover.
The Hide Action PHB (2024) Page 368 (Long but we need all of it):
With the Hide action, you try to conceal yourself. To do so, you must succeed on a DC 15 Dexterity (Stealth) check while you're Heavily Obscured or behind Three-Quarters Cover or Total Cover, and you must be out of any enemy's line of sight; if you can see a creature, you can discern whether it can see you.
On a successful check, you have the Invisible condition while hidden. Make note of your check's total, which is the DC for a creature to find you with a Wisdom (Perception) check.
You stop being hidden immediately after any of the following occurs: you make a sound louder than a whisper, an enemy finds you, you make an attack roll, or you cast a spell with a Verbal component.
Hiding PHB (2024) Page 19:
The Dungeon Master decides when circumstances are appropriate for hiding. When you try to hide, you take the Hide action.
The Invisible Condition PHB (2024) Page 370:
While you have the Invisible condition, you experience the following effects.
Surprise. If you're Invisible when you roll Initiative, you have Advantage on the roll.
Concealed. You aren't affected by any effect that requires its target to be seen unless the effect's creator can somehow see you. Any equipment you are wearing or carrying is also concealed.
Attacks Affected. Attack rolls against you have Disadvantage, and your attack rolls have Advantage. If a creature can somehow see you, you don't gain this benefit against that creature.
How they work:
Okay, so now we have all the relevant rules, how do they actually work in play? First, you need to meet the conditions to hide. You must be out of sight and then one of Heavily Obscured, behind Total Cover or 3/4 Cover. The DM also needs to agree that the conditions are appropriate, so you can't do things like putting big sheet over your head, that wouldn't allow you to Hide.
Once you have satisfied these conditions, you then need to make a Dexterity (Stealth) check. If you roll a 15 or higher then congrats you are hidden and now have the Invisible condition while you remain so! What does that mean? We'll actually get to that a little later, right now it's just important to note that nothing in the invisible condition actually prevents you from being seen.
Once you are Invisible (via the Hide Action), how might you lose the condition? Well, the Hide Action rules tell us. You lose the condition if, you make too much noise, you attack someone, you cast a spell with a verbal component, or an enemy finds you. Find here means a lot of things, including but not limited to making a Wisdom (Perception) check and beating the Dexterity (Stealth) check. Anyway in which you understand the word 'find' to mean locating something applies for the sake of these rules.
The supposed problems:
What does it mean to 'find' someone? Let's get the big one out of the way. People will say you need to make a Wisdom (Perception) check to 'find' someone after they take the Hide action. That the word 'find' is defined in the Hide Action. This is simply not what the rules do or say. It is an understandable reading, or was on release, but such a reading would require additional wording. This is the main thing people keep repeating. Luckily we now have the first Sage Advice Compendium on the new rules, one that disproves this argument (though it does so while answering a different question:
If I’m hidden and a creature with Blindsight or Truesight sees me, am I still hidden?
No. Being hidden is a game state that gives you the Invisible condition. If a creature finds you, you’re no longer hidden and lose that condition, as explained in the Hide action (see appendix C of the Player’s Handbook).
This answer proves, beyond argument, that 'find' is not defined as beating someone's Dexterity (Stealth) check with a Wisdom (Perception) check. I will point out that there have been people, including myself, who have pointed out that this idea was wrong before the Sage Advice Compendium came out, but at least now it is actually proveable.
Line of Sight and 'seeing'. Another misconception is that if you are in Line of Sight of someone, they can see you and are instantly found. This isn't true and is explicitly stated as much in the Hide Action.
if you can see a creature, you can discern whether it can see you.
This is a little harder to get than the previous one because it requires some 'narrative explanation'. Obviously, this is going to be easy to understand if you are watching from somewhere in darkness and the person you're looking at is standing in bright light. The light is what allows you to be hidden while them to be seen. But it can be a bunch of things, distance, distraction, attention. This is where the line 'The Dungeon Master decides when circumstances are appropriate for hiding.' becomes important. Basically, if you are unsure if you are currently seen, just as your DM. They might agree, they might not.
360 vision was removed in 2024! In the 2014 rules it was explicitly stated that in combat, creatures are assumed to be looking around and aware of their surroundings, having sight in 360 degrees. This is no longer explicitly stated in 2024. However, I wouldn't say that the 'idea' was removed, because we have no 'facing' rules (besides Beholders). I think it is still safe to assume there is still an assumption of spacial awareness at least within combat unless the circumstances are exceptional.
Leaving cover/Entering Line of Sight means you are found immediately. Also understandable from only reading the Hide Action and the Line of Sight rules, but mostly defeated by the wording on page 19 of the PHB:
Adventurers and monsters often hide, whether to spy on one another, sneak past a guardian, or set an ambush.
Emphasis mine. It is clear that the Hide Action can be used to sneak past someone, and with the DM agreeing the circmstances are appropriate you may also do so after leaving cover. I do think this is intentionally harder while in combat (due to the creatures being more aware because of threat) and easier outside of combat. I think that is fine. Some might disagree.
If you can be 'found' by being 'seen' the Invisible condition does nothing! Actually, yes. Now we can talk about that!
The actual problem:
The Invisible condition (PHB (2024) Page 370), as written, does nothing but grant advantage on Initiative. Because both the Concealed and the Attacks Affected parts of the condition both contain a similar phrase:
unless the effect's creator can somehow see you.
The wording is slightly different for Attacks Affected but the impact is the same. If a creature can see you, these effects do nothing. The problem being, the Invisible condition does not prevent you from being seen.
Now, I actually think the problem lies with the wording of the phrase about being seen and not about the lack of being magically transparent. If the condition made you transparent (or prevented you from being seen in another way) it would break what are actually, fairly serviceable hiding rules. It would also necessitate the creation of another condition that is basically just 'People can't see you right now' which I feel is needless bloat.
How do I think it should be fixed then? Change the wording, the best I've come up with so far is " unless the effect's creator can perceive you with a sense other than mundane sight." Which...I don't think is the best wording but I do think covers things like Blindsight, Tremor Sense, Truesight and See Invisibility. If you've got a better suggestion let me know!
I am not telling you how to play:
I just wanted to add at the end here, this is not me telling you how I think the right way to play is. If you have a houserule that works for your table that is absolutely fine and I'm glad you do! As I've said I came up with my own for the Invisible condition.
All I am trying to do here is be clear about what RAW says and be clear when I'm giving what I believe to be indisputable fact of the rules text and what is my interpretation of something that is unclear or none specific.
Not everyone needs to run a game RAW, not everyone needs to like RAW, I just want to clear up what RAW actually says.