How does Heavily Obscured work?

In one of the dungeons in my campaign, there is a glyph of warding that creates Stinking Cloud (to bully my players while the Yuan Ti immune to poison attack them) and one of the effects is the area is Heavily Obscured.

After reading the rules saying "You have the blinded condition while trying to see something in a Heavily Obscured space", I am a little confused. Does "in a Heavily Obscured space" mean while you're in a Heavily Obscured space (because you can't see anything outside) or when the thing your seeing is in a Heavily Obscured space (because it's hard to see something that's in the  HO area) . Both make sense, so it is hard to figure out which one is the correct interpretation.

This one is just a hornet’s nest.

There is no universally accepted answer, with lots of people coming firm on both sides. 
Rather than re-litigate, I’ll say the best choice is to make a ruling, and then stick to it in the future, whichever way you decide to go.

Alr, Ima choose whichever lets me bully my players (they my friends dw) via them not being able to do anything and being slapped by a bunch of snake people 

Both. 

A Heavily Obscured area—such as an area with Darkness, heavy fog, or dense foliage—is opaque.

Quote from Xalthu >>

This one is just a hornet’s nest.

There is no universally accepted answer, with lots of people coming firm on both sides. 
Rather than re-litigate, I’ll say the best choice is to make a ruling, and then stick to it in the future, whichever way you decide to go.

Yup. You know who you are out there. Leave it alone. The GM has already decided what he's going to do.

It's the second one.

The term Heavily Obscured area describes an area.  Specifically, it's an area that is heavily obscured.  Therefore, the inside of that area, including everything that is located within it is impossible to see, because they are obscured from view.  So, when you attempt to look at such things, you are mechanically blinded while trying to do so.

Quote from Erik_Soong >>

Both. 

A Heavily Obscured area—such as an area with Darkness, heavy fog, or dense foliage—is opaque.

 This is my ruling too, but as Xalthu said: "There is no universally accepted answer, with lots of people coming firm on both sides."

ZardiacTheW1zard, here's the most recent thread about this topic in the subforum: a fog cloud and an archer walk into a bar. I left some links to similar threads in this reply.

My humble recommendation would be to revisit those and try to get a sense of the consensus on your own.

EDIT: for clarity.

Read some of the things in the "A fog cloud and an archer walk into a bar" bit

Good to see that I'm not the first person baffled by this lmao

How i rule it a Stinking Cloud is opaque, thus obscure vision by blocking Line of Sight through it meaning you can't see within nor past it.

I would hope everyone has personal experience of Heavily Obscured areas - e.g. fog, cloudy water, or a dark basement. It's very simple, stuff within the heavily obscured area cannot be seen with visual senses. 

And I'm sure we'd all love it if that's what the rules actually told us... but, well, the other threads hash those arguments out, so no need to go into it here.

A map location is either Heavily Obscured or not. If it is Heavily Obscured, you cannot trace lines of sight either into or through that area. It's literally that simple.

The problem people have is applying this rule. For example, consider the situation where it's a moonless night and there's a campfire off in the distance. The campfire clearly illuminates the area immediately surrounding it. However, it doesn't illuminate all of the area back to our observer. That means you've got a few squares that are at least dimly lit - but a bunch of Heavily Obscured squares between you and them. Applying our simple rule means you can't see the campfire (since you can't see through Heavily Obscured squares) - which is a counter-intuitive result for many players.

There's also the issue with Illusions. Ordinarily, a spell cannot create a named condition (such as "Heavily Obscured") unless it explicitly states it can do so. So if I throw up a Silent Image of a wall, the expectation is that one cannot see on the other side of the illusionary wall. However, since Silent Image provides neither Cover nor Heavily Obscured, I can see through the wall. This seems silly but consider that a Silent Image that does block line of sight is actually a cheaper, better version of Darkness. On the other hand, an illusion like Mirage Arcana strongly implies that the wall would block sight (as well as provide Cover) without explicitly stating it does so.

Quote from Wysperra >>

Quote from Xalthu >>

This one is just a hornet’s nest.

There is no universally accepted answer, with lots of people coming firm on both sides. 
Rather than re-litigate, I’ll say the best choice is to make a ruling, and then stick to it in the future, whichever way you decide to go.

 

Yup. You know who you are out there. Leave it alone. The GM has already decided what he's going to do.

 

 I feel called out. 

At any rate, for a stinking cloud, it would be that if you are trying to see things that are within the area that is heavily obscured, you have the blinded condition. 

Because it is a cloud of gas, like a fog cloud, if you are within the cloud (within the area that is heavily obscured) you wouldn't be able to see out because the spell creates an effect that blocks sight. So you would be blinded while within the cloud as well. 

Quote from VerilyRaze >>

 There's also the issue with Illusions. Ordinarily, a spell cannot create a named condition (such as "Heavily Obscured") unless it explicitly states it can do so. So if I throw up a Silent Image of a wall, the expectation is that one cannot see on the other side of the illusionary wall. However, since Silent Image provides neither Cover nor Heavily Obscured, I can see through the wall. This seems silly but consider that a Silent Image that does block line of sight is actually a cheaper, better version of Darkness. On the other hand, an illusion like Mirage Arcana strongly implies that the wall would block sight (as well as provide Cover) without explicitly stating it does so.

 I honestly don't understand why people can't understand the rules. Illusions obviously block line of sight while a creature is unaware of the illusion, however most illusions become translucent when a creature realizes it is an illusion (at least that was the rule in 5e).  

Re: Silent Image vs Darkness :

Silent Image has to create an illusion of something filling the space, you can't make an illusion of "nothingness" with Silent Image, you need something like Hallucinatory Terrain to do that. So you can create an illusion of a box up to 15 ft x 15 ft x 15 ft covering up the party which blocks line of sight, but it might also arouse suspicion if there is a giant box in many locations, especially if it moves around, which would cause nearby creatures to investigate and realize it is an illusion thus "break" the illusion and allow them to see you - just as your party know the box is an illusion thus can see out through the illusion. You could also do a wall, but again, most creatures will notice a wall where there didn't use to be one.

Darkness, I agree is kind of a bad spell. But at least in theory, a patch of darkness should be less noticeable to enemies than an illusory box/wall. Mechanically, this is kind of true because they have disadvantage / autofail Perception checks. However, most DMs I've played with rule that a bubble of Darkness is just as noticeable as an illusion. Darkness is also a larger area 15 ft radius rather than 15 ft cube so you can probably fit the whole party in an area of Darkness, but it's pretty unlikely you could fit the entire party within a Silent Image. The main advantage of Darkness in practice is that even if the enemies notice the Darkness they still cannot see who is inside of it, so you could potentially escape without the guards knowing who you are / being able to recognize you. Whereas if a creature notices your Silent Image they can see through it thus know exactly who you are and put out a bounty for you.

The Problem with RAW

The main problem with RAW is the use of Heavily Obscured for both illumination (darkness) and obscurement (thick fog), when these work very differently in reality. However it is kind of an impossible task because there are many edge cases to consider. For example, if you've never hidden in a bush before IRL, I recommend you try it because it is very possible to hide in a bush, and be able to peak out between the leaves while being almost invisible to people outside of the bush, and it being true that people on opposite sides of the bush cannot see each other. 

Hence Rule 0 of D&D: if RAW is preventing your fun, change the rules.

I'm ruling that an illusion blocks your Line of Sight. You don't see what's behind it. But it doesn't create Cover since it's not a real obstacle ("Cover provides a degree of protection to a target behind it")

So if you, for some random reason, shoot an arrow or throw a pebble at a door or a box, and that object is an illusion, your arrow or pebble would reach the other side.

Btw:

- Minor Illusion + Attacking question
- Clarity on Silent/Major Image

Quote from Agilemind >>

I would hope everyone has personal experience of Heavily Obscured areas - e.g. fog, cloudy water, or a dark basement. 

 Why yes, I have, and my personal experience say "reality is also inconsistent". In reality:

• If you're in a darkened area, you can see out, outsiders cannot see in, and the darkness does not block line of sight.
• If you're in the middle of a sufficiently dense cloud, you cannot see out, outsiders cannot see in, and the cloud blocks line of sight.
• Essentially all forms of obscurement other than darkness work in the same way as the cloud, though you have the occasional edge case such as glare.

What this means is that it was a mistake to say that darkness is heavily obscured, darkness should be 'blocks vision into the area' and heavily obscured should be 'blocks vision into, out of, or through the area', but, well, you deal with the rules that you actually have, not the rules that you wish they'd written, and they rules they've actually written... are inconsistent.

 but, well, you deal with the rules that you actually have, not the rules that you wish they'd written, and they rules they've actually written... are inconsistent.

Well good job jumping off the cliff because your friend told you it was a fun thing to do. 

Quote from Agilemind >>

Well good job jumping off the cliff because your friend told you it was a fun thing to do. 

 When I'm running a game I routinely ignore RAW for vision, but this thread is rules and game mechanics.