D&D 5E What does it mean when a Web spell is "layered across a floor, wall, or ceiling?"

[nevin]

5 ft deep would be like 10,000 castings of web. needs to be 7th level

 

[el-remmen]

5 ft deep would be like 10,000 castings of web. needs to be 7th level

"The webs fill a 20-foot cube from that point for the duration."

Sounds like a lot less than one casting to me!

 

[el-remmen]

This.

If you don't have two opposed anchor points, the web can be cast on a single flat surface, and will layer on itself to a depth of 5'.

If you do have two opposed anchor points, you can stretch it taller.

So if you've got a 20' x 20' room with a ceiling up to 20' high, you can fill the whole room.

If you've got a 20' x 20' room with a ceiling 30' high, you can fill the whole room up to the 20' level, or leave the top and bottom 5' open, or fill the top 20' and leave the bottom 10' open (maybe to help combat flyers).

If you've got an empty 30' x 30' x 30' room, you can only fill a 20x20 section of it up to 5' deep.

If you've got a 30' x 30' room with a 20 ceiling, you can anchor on the floor and ceiling and fill up to a 20' x 20' x 20' section if it.

If you've just got two 50' tall trees 15' apart, you can put a web up to 20' high between them.

If you've got a bunch of scattered trees 20' tall or taller with anchor points within 20' of each other, you could make up to a 20x20x20 web in the forest.

This is the best explanation and the spell should include some example like this.

 

[MarkB]

If I am understanding (and I am not sure I am), despite what the spell says the web will never actually collapse on itself unless the caster specifically says, "I don't layer them." And I am not sure why anyone would do that. Just seems like a confusing way to describe the spell.

Basically, it's just saying (a) if you cast it in open air without any solid surfaces within its volume (like if you're in an aerial battle 200' up and you cast it on some nearby flying opponents) then it will work initially but it'll collapse after a round, and (b) if you cast it on a flat surface with no surrounding anchor points within its area, you won't get a big free-standing 20-foot cube of web like an oversized gelatinous cube, you'll just get a layer of web on the floor.

 

[Lanefan]

Basically, it's just saying (a) if you cast it in open air without any solid surfaces within its volume (like if you're in an aerial battle 200' up and you cast it on some nearby flying opponents) then it will work initially but it'll collapse after a round, and (b) if you cast it on a flat surface with no surrounding anchor points within its area, you won't get a big free-standing 20-foot cube of web like an oversized gelatinous cube, you'll just get a layer of web on the floor.

In this case I'd say that if you cast it on a flying opponent the opponent itself would act as its own anchor point(s) and thus get gummed up for the full duration, but could (if not using wings to fly) still fly away. If-when it landed with the web still in effect, it'd become stuck to the ground at that point.

That said, I've personally always had it that you need at least two fixed anchor points (can be as simple as a pole and the ground) for the webs to form; meaning that casting it in mid-air or on a flat open surface will produce nothing of any use. A single pole plus the ground would give a wigwam-shaped web to the height of the pole only. It's a spell best cast in tight-ish underground areas or in a forest where there's lots of anchor points.

It's never come up in my life but I'm thinking of it now anyway: what happens if web is cast on or under water?

 

[el-remmen]

It's never come up in my life but I'm thinking of it now anyway: what happens if web is cast on or under water?

I thought the 1E DMG said so, but looking now all it says is that web must have two anchor points. So at least some time in the past it had that stipulation (which is probably why I had that vestigial feeling that it should only work that way).

 

[EzekielRaiden]

I seriously doubt the weba would be 5 feet deep. 5 inches would be too much. a freakishly strong webline would be the thickness of 14 gauge wire

The spell explicitly says that it covers flat surfaces to a depth of 5 feet: "Webs layered over a flat surface have a depth of 5 feet."

 

[GMMichael]

The spell explicitly says that it covers flat surfaces to a depth of 5 feet: "Webs layered over a flat surface have a depth of 5 feet."

. . . except that's in clear contrast with WotC's "20 foot cube" design.

 

[EzekielRaiden]

. . . except that's in clear contrast with WotC's "20 foot cube" design.

Okay. I"m just telling you what the text of the spell explicitly says. If you choose to layer it on a flat surface, it creates a layer of webbing 5' deep. That is explicitly stated in the spell itself. The spell produces an effect if either anchored to at least two points, or layered across a flat surface, such as a wall, ceiling, or floor. If it is layered across a floor, then the webs layer on that surface to a depth of 5 feet.

I don't really see how there can be any disagreement that that's what happens. It's...really quite cut and dried. Even with my (many, many) issues with 5e's (over)reliance on "natural language", I don't see how it's possible to interpret this as anything other than what is specifically spelled out here.
If the webs aren't[...]layered across a floor, wall, or ceiling, the web collapses on itself, and the spell ends at the start of your next turn. Webs layered over a flat surface have a depth of 5 feet."

Hence, the webs do not collapse if they are layered across a floor, wall, or ceiling, and, verbatim, "[w]ebs layered over a flat surface have a depth of 5 feet."

You may protest that this is unrealistic, or that it is too powerful, or that it should have been written differently. All of those are valid complaints. But I don't really see how anyone can deny that the above is what the spell does.

If it helps, perhaps consider the 20' cube to collapse onto the floor, wall, or ceiling to a depth of five feet?

 

[MarkB]

It's never come up in my life but I'm thinking of it now anyway: what happens if web is cast on or under water?

I'd treat the water as air - it doesn't count as a solid surface to anchor the web, but nor does it hinder it (maybe crashing waves would break it apart). Cast it underwater in an area where there are some solid anchor points around and it'll work just fine.