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

[Oofta]

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?

Glass is still a physical obstacle, by a strict reading of the rules the fact that glass is transparent has nothing to do with whether it's completely between the caster and target. It's easier to state that any physical object stops spells, but as always do what makes sense.

I might rule that something like the Catapult spell might send the object you're catapulting would be unaffected. A Lightning Bolt could shatter it and go through. But other spells? Magic Missile does nothing to physical objects, I see no "oomph" behind them, so they would be stopped. A fireball would hit the pain of glass and go off, etc..

In other words, the way I would rule is that the spell has to have the ability to break or pierce the obstacle and keep going in order to work.

 

[Oofta]

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.

If the spell says "target you can see" I wouldn't allow it either. But something like a lightning bolt? Or take Catapult which throws an object of the caster's choice. That's a different story.

Maybe there should be two standards? The "arrow" test and the "paper airplane" test? It gets weird. Let's say someone is hiding behind a tapestry. Based on strict reading, most spells could not target the person, even ones that don't include the "must see". But that tapestry isn't really more protection than any armor or heavy clothing they may wear.

Some spells like (random spell here) Aganazzar's Scorcher to me should work because you're just picking a direction and, like lighting bolt, it can affect multiple creatures in a line. But would the Fire Bolt cantrip hit the creature behind the tapestry or just set the tapestry on fire? Does it matter if the tapestry is being used as a makeshift cape with hood and the target is looking away from you?

The rules are simple until they aren't. That's why we have rulings over rules because no set of rules will ever cover every edge case.

 

[greg kaye]

...
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.

I guess the big question is whether a target can be targeted indirectly by means other than with an area of effect. My thoughts return to the likes of magic missile, feeblemind and healing word.

 

[Paul Farquhar]

Glass is still a physical obstacle

Dictionary definition:

obs·tacle
[ˈɒbstək(ə)l]

NOUN

1. a thing that blocks one's way or prevents or hinders progress:

If the glass does not block or hinder, it is not an obstacle.

 

[Dausuul]

There are two key rules in play:

• Total cover will block a spell unless the spell says otherwise. (PHB Chapter 10, "Casting a Spell," the section on targets.)
• Many spells specify that you must be able to see the target.

The questions then are, first, what counts as total cover? And second, what qualifies as "seeing?" I'd answer the first with "any solid barrier," and the second with "any form of visual perception or perception that is noted by the rules as equivalent to vision" (e.g., blindsight) -- with the caveat that the perception must be "live," so to speak; you can use a mirror but not a portrait.

1. the target is within range but on the other side of a transparent, solid barrier such as glass.

Such a barrier counts as total cover. You cannot target that creature with any spell, unless the spell notes that it ignores cover (e.g., sacred flame).

2. the target is within range but cannot be directly seen due to an inability to turn or due to an obstruction such as a wall but you are still able to view the target due to something such as a local, perhaps handheld mirror.

If "an obstruction such as a wall" is what prevents the target being seen, then it has total cover from the wall; whether you can see it doesn't matter, you can't target it because of cover.

If something else prevents you seeing the target directly (e.g., a fog cloud spell), you are still visually perceiving the target. As I said above, I consider this good enough to target.

3. the target is within range and on the other side of a restriction to vision such as containment but you are still able to view the target thanks to an ability such as clairvoyance.

See previous. Indirect vision is still vision, but total cover blocks the spell whether you can see it or not.

 

[Dausuul]

Then how does the magic "find" the object(s) sought?

The D&D rules do not attempt to answer this question. The goal of the rules is to make it clear in 95% of cases what a given spell can or cannot do (with the remaining 5% being left to DM adjudication). The rules are not trying to explain how the spell does what it does, nor to formulate a consistent theoretical basis for magic*.

IMO, this is very much the correct approach. <soapbox> There is a widespread idea that a magic system where the principles of magic are laid out in detail is more predictable than one where no such principles are given. What I've noticed is that this is not, in practice, the case. Just like real-world science, there is a vast gap between theoretical first principles and actual practical application, and you can stuff all kinds of "magic technobabble" into that gap to justify whatever ass pull you have in mind. Trying to evaluate the technobabble based on first principles is like trying to use particle physics to evaluate your mechanic's explanation for why the car won't start. </soapbox>

For a magic system to be predictable (which an RPG with spellcasters very much needs), it must specify not principles but outcomes. The rules don't need to say how the magic works. They do need to make it clear that spell X can do Y and cannot do Z.

*They put a little bit of theory into 5E with the sidebar about the Weave. No previous edition felt the need to bother with this; the Weave was a Forgotten Realms notion that didn't apply in other settings. And even in 5E, that sidebar ties into nothing else in the rules and can be dispensed with at will.

 

[Oofta]

Dictionary definition:

If the glass does not block or hinder, it is not an obstacle.

Try walking through standard commercial glass door and tell me again how it's not something that hinders you. Tell the birds that fly into windows that their progress has not been hindered.

Redefine the word if you want. Glass is transparent so it doesn't obstruct the visible spectrum of light. It still stops just about everything else.

If you stretch the definition enough, solid walls aren't obstructions because they don't stop radar.

 

[Deset Gled]

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

The very existence of this thread is evidence that "DM call" may not work for every table as well as it does for yours. Adopting, or at least discussing, expanded rules for the table is a way to promote communication, consistency, and general harmony within the gaming group. 3.5e's rules are simple one set of more detailed rules that could work, and have the benefit of having been tested and discussed by others in great detail.

 

[Lanefan]

The D&D rules do not attempt to answer this question. The goal of the rules is to make it clear in 95% of cases what a given spell can or cannot do (with the remaining 5% being left to DM adjudication). The rules are not trying to explain how the spell does what it does, nor to formulate a consistent theoretical basis for magic*.

IMO, this is very much the correct approach. <soapbox> There is a widespread idea that a magic system where the principles of magic are laid out in detail is more predictable than one where no such principles are given. What I've noticed is that this is not, in practice, the case. Just like real-world science, there is a vast gap between theoretical first principles and actual practical application, and you can stuff all kinds of "magic technobabble" into that gap to justify whatever ass pull you have in mind. Trying to evaluate the technobabble based on first principles is like trying to use particle physics to evaluate your mechanic's explanation for why the car won't start. </soapbox>

For a magic system to be predictable (which an RPG with spellcasters very much needs), it must specify not principles but outcomes. The rules don't need to say how the magic works. They do need to make it clear that spell X can do Y and cannot do Z.

And in saying that spell X can do Y but not Z there IMO also needs to be a why in there somewhere. Put another way, if the rules don't need to say how the magic works then I-as-DM am left to make it up for myself; and having at least a vague idea of what the designers had in mind would make that process much easier (and if the designers didn't have anything in mind that's an unrecoverable fail on their part).

It's trivially easy to lay down a few basic principles:

--- if a spell causes anything physical - a bead, an arrow, etc. - to go from caster to target(1) then any physical obstacle will block it
--- if a spell does not cause anything physical to travel from caster to target(1) but requires a visible target, then transparent physical obstacles do not hinder that spell, nor do they hinder visible spell effects e.g. rays, dancing lights, etc. from functioning as intended
--- if a spell neither requires a visible target nor causes anything physical or visible to travel from caster to target then it can be cast anywhere within the caster's range without regard for obstacles of any kind(2)
--- a roll for aiming is always required when caster cannot see the target point, person(s), place, or area.

1 - or from somewhere else to target e.g. Call Lightning causes lightning to travel from the sky to the target
2 - excepting obstacles that block all magic e.g. a lead-lined wall; and this is specifically intended to allow blind-casting into previously-unseen areas

*They put a little bit of theory into 5E with the sidebar about the Weave. No previous edition felt the need to bother with this; the Weave was a Forgotten Realms notion that didn't apply in other settings. And even in 5E, that sidebar ties into nothing else in the rules and can be dispensed with at will.

Yes; and though I've never 100% bought into Weave theory myself I appreciate it as at least being a halfway-thought-out attempt at explaining how and why magic works the way it does.

 

[Lanefan]

Try walking through standard commercial glass door and tell me again how it's not something that hinders you. Tell the birds that fly into windows that their progress has not been hindered.

Redefine the word if you want. Glass is transparent so it doesn't obstruct the visible spectrum of light. It still stops just about everything else.

When you're casting Hold Person at someone you can see on the other side of a window, what is physically moving from you to the target for the glass to stop?

Or if looked at yet another way, you're not summoning the magic into you-the-caster here, you're summoning it to manifest and do something over there.

Same as with a Lightning Bolt - there's nothing physically travelling between me-the-caster and where I start the bolt, and so I should be able to start it at a point I can see through a window.

If you stretch the definition enough, solid walls aren't obstructions because they don't stop radar.

Exactly, which is why many spells without physical elements or targeting requirements should be castable "blind". I even went so far as to add a fourth component "L" to all spells, to indicate whether line of sight/effect was required or not without having to write it out every time.