D&D General "that you can see", "line of sight", glass, mirrors, ~clairvoyance, blindsight, and anything else.

[Deset Gled]

Does glass provide total cover?

Does it provide total cover against a sniper rifle?

What if it's made from bullet-proof glass?

It's up to the DM to decide if something provides cover, and that is going to depend on what you are attacking with. Which is why we have human DMs to make the judgment call.

FWIW, 3.Xe had a formal definition for Line of Effect as a distinctly different mechanic from Line of Sight. Some magic effects required one, some the other, and some both. The rules can be found in the SRD and could be easily adapted to 5e by any group that wanted a bit of a crunchier answer than just "DM fiat".

 

[greg kaye]

... The whole line of effect thing was added/clarified in 3, it's not new to 5E.

From a search of site:dndbeyond.com/spells/ "Line of effect", it doesn't seem that the topic is mentioned directly in relation to spells in 5e at all.

Perhaps, if a concept like line of effect still applies, may now relate more to spells like gust of wind, wall of X, and moonbeam.

Arguably and perhaps aesthetically, spells like my mentioned magic missile don't need to have a direct line of effect and spells like feeblemind have effects that are directly related to the target.
Spells like firebolt and eldritch blast require spell attacks and, in these cases, I guess that a lot may depend on views on how magic works.
All the same, spells like guiding bolt, which deal radiant damage, or healing word, which have features related to sound, may deal better with (that rarely occurring substance in 5e) glass.

 

[Paul Farquhar]

The rules can be found in the SRD and could be easily adapted to 5e by any group that wanted a bit of a crunchier answer than just "DM fiat".

What would you? DM call works just fine, and covers every possible eventuality.

 

[greg kaye]

DM call works just fine, and covers every possible eventuality.

... and a DM's call to use materials from previous rules editions for reference is also fine.
It just wouldn't be 5ed RAW.

 

[TaranTheWanderer]

How else do you think rogues take no damage if they're successful on dex saves?

View attachment 286175

This is why Minor illusion is actually a great spell. Create a 5X5 foot box and move in and out of it on your turn. While in it, everything is at disadvantage to hit you and you can't be targeted by spells that require sight, like magic missile. Obviously, not fool proof but very helpful.

So are people who live in glass houses, immune to spell effects.

Yet another reason why they should not throw stones.

 

[Oofta]

Maybe. The rules are actually very vague:

Note, the use of the word "can", which indicates uncertainty, and the absence of the word "glass" from the list of things that can provide cover. Is glass an obstacle? Only the DM knows.

I read that "can" as they can provide different levels of cover, from half to total. But technically true, it's up to the DM how much of your target you can see that is not blocked by cover.

 

[Oofta]

Yep, Dispel got both nerfed and made "safer" over time, as when it was area-effect you could easily hit things you didn't want to hit. I far prefer the higher-risk higher-reward version.

3e clarified in with regards to darkness, fog, or other visual obstruction that wouldn't otherwise physically block the spell; and got it right. I don't recall it going into detail about the can't-cast-through-glass bit, though.

And I'm pretty sure 3e still had some spells you could shoot blind e.g. behind a door or wall.

In 3.5 Chapter 10: Magic they clearly spell out line of effect (emphasis mine):

Line of Effect: A line of effect is a straight, unblocked path that​

indicates what a spell can affect. A line of effect is canceled by a solid​

barrier. It’s like line of sight for ranged weapons, except that it’s not​

blocked by fog, darkness, and other factors that limit normal sight.​

​

You must have a clear line of effect to any target that you cast a​

spell on or to any space in which you wish to create an effect...​

It states any solid barrier, we always ran it that it could include a pain of glass.

 

[Oofta]

From a search of site:dndbeyond.com/spells/ "Line of effect", it doesn't seem that the topic is mentioned directly in relation to spells in 5e at all.

Perhaps, if a concept like line of effect still applies, may now relate more to spells like gust of wind, wall of X, and moonbeam.

Arguably and perhaps aesthetically, spells like my mentioned magic missile don't need to have a direct line of effect and spells like feeblemind have effects that are directly related to the target.
Spells like firebolt and eldritch blast require spell attacks and, in these cases, I guess that a lot may depend on views on how magic works.
All the same, spells like guiding bolt, which deal radiant damage, or healing word, which have features related to sound, may deal better with (that rarely occurring substance in 5e) glass.

In 5E Chapter 10: Spellcasting - Targets

A Clear Path to the Target​

To target something, you must have a clear path to it, so it can’t be behind total cover [walls, trees, other obstacles].​

​

If you place an area of effect at a point that you can’t see and an obstruction, such as a wall, is between you and that point, the point of origin comes into being on the near side of that obstruction.​

Under Chapter 9: Cover - Total Cover

A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.​

Just because glass happens to be transparent doesn't change the fact that it is still a physical object. Run it however you want of course, I'm just repeating what the book says.

P.S. I do have a habit of using phrases from previous editions at times, I still think line of effect is the best wording whether or not 5E uses it.

 

[Paul Farquhar]

It’s like line of sight for ranged weapons,

You could shoot someone with a crossbow through ordinary glass. You might treat it as light cover (+2 AC).

And clearly Hamlet can target someone through a tapestry with a rapier.

It might be an object, but is it an obstacle?

 

[TaranTheWanderer]

You could shoot someone with a crossbow through ordinary glass. You might treat it as light cover (+2 AC).

And clearly Hamlet can target someone through a tapestry with a rapier.

It might be an object, but is it an obstacle?

attacking through a tapestry might be an attack made at disadvantage. Not sure you're allowed to target someone with a spell though since you can't 'see' them. unless the DM says you can see their 'bulge' through the tapestry? idk.