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If you were outside during the day and you cast darkness above you somehow, would the darkness spell cast a shadow?

If you cast darkness in a tunnel, and the only source of light was from one end of the tunnel only, would the other side of the darkness spell remain illuminated or would it be plunged in shadow (non-magical darkness)?

The description of the darkness spell says that "light can't illuminate". I would therefore posit that it also does not pass through it either.

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No, darkness doesn't cast a shadow.

At least, it doesn't without a particular DM making it a table rule — which would be a totally reasonable ruling to make. To tackle the question though, we must consider the default baseline from which such rulings would be made, avoiding assuming rulings that give us a result from circular reasoning.

Darkness not casting a shadow is non-intuitive, but magical darkness is inherently non-intuitive and operates by its own idiosyncratic rules.

I've emphasised the relevant parts of its effect description (PBR p. 86; PHB p. 230):

Magical darkness spreads from a point you choose within range to fill a 15-foot-radius sphere for the duration. The darkness spreads around corners. A creature with darkvision can’t see through this darkness, and nonmagical light can’t illuminate it.

The stipulation that it's effect is limited to a radius of 15 feet, and that its effect is to prevent illumination, not penetration of light, means that it does not and cannot alter light levels outside its area of effect.

Contrast this effect description of darkness with that of fog cloud: the latter's description simply says that it creates fog in a given area, and then leaves it as an exercise for the reader to extrapolate from our shared understanding of real-world fog — such as the fact that fog impedes the passage of light — with the help of the game's specific rules for obscured vision. Darkness, by contrast, does not try to leverage our intuitions about "magical darkness" — as none can be expected of us1 — and instead gives specific effects. These effects are sufficient for most groups, so that groups who don't care (or who prefer a non-scientific fantasy experience) can get on with the game without having to tackle the question "but how does it work?!" with lengthy deliberations first.2

It could be argued that the line "A creature with darkvision can’t see through this darkness" means that light is entirely prevented from passing through. However, such an extrapolation would be a ruling limited to the ruling DM's game, as other DMs will not all also make the same ruling. (Since how darkvision operates is idiosyncratic and non-lawlike in the same way as how magical darkness does, we cannot reason from how it operates to how darkness operates, without a DM adding even more interpretive rulings.) Since such a ruling is an addition and not universal to all possible DMs, and because magical darkness is inherently illogical, that extrapolation can't be considered the default, baseline case.


1. Those of us who have a specific metaphysical reality in mind that does create intuitions about how magical darkness operates are precisely those who would want to make rulings about darkness in order to satisfy our intuitions and to make the spell better match our imagined setting. This is exactly what the permission to houserule, that the game gives DMs, is designed to accommodate. For the rest of us, the game doesn't assume anything, and gives us bare effects for things that are not transparent to the usual intuitions of modern humans, like darkvision and the darkness spell.

2. In my own games, I'm likely to rule that it does cast a shadow because I tend toward classicism in my campaign metaphysics — if the issue ever comes up, which I expect it likely won't. Except that, if I'm running a romanticist campaign based on my ontological Chaos premise, I'm likely to say that it doesn't cast a shadow and neither does its contents, for no reason other than "because Chaos." So, there you go: it very much depends on the DM and campaign.

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$
    – mxyzplk
    Sep 8, 2018 at 20:31
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    \$\begingroup\$ I know I picked this as the correct answer because it's really the best one, but this is truly still an unresolved issue for me....I still think Darkness casts a shadow. Not a magical darkness shadow, just a normal shadow. \$\endgroup\$
    – Escoce
    Jul 29 at 20:32
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    \$\begingroup\$ @Escoce Of course it casts a shadow, if it didn't, you could see everything on the other side perfectly clearly, so it'd be called Globe of Invisibility. \$\endgroup\$
    – biziclop
    Jul 31 at 14:59
  • \$\begingroup\$ The spell only says that creatures with darkvision cannot see through this darkness. You mean that we cannot extrapolate from that info because we don't know how darkvision works, but the only way that makes sense is if creatures without darkvision can see through the darkness. I.e. the not-see-through part is tied to darkvision. It is, imo, pretty clear that no one, not even those with darkvision, can see through. That means light is blocked and there is a shadow. \$\endgroup\$ Jul 31 at 22:17
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    \$\begingroup\$ As I see it: It's magic. Not being able to see through, and casting a shadow, are not the same. Light being an electromagnetic wave is a real-world idea that doesn't have to hold sway. Magic breaks natural law. It can do weird and nonsensical things. I have a narrow hallway whose cross-section is small enough Darkness fills it. The only light is a lantern on the other side. I can't "see through it" so things in and beyond the Darkness, I can't see. But my part of the hallway is still illuminated (by something I can't see). It is true this makes no physical sense; it's also irrelevant. \$\endgroup\$
    – Ton Day
    Aug 1 at 9:14
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When I first read the spell description, I also was surprised about the:

« [...] nonmagical light can't illuminate it. »

At the same time they say that magical light created by a cantrip or a spell of level 1 or 2 will be dispelled, which I would interpret as: « Any light entering the darkness area is destroyed. »¹

That, in effect, means anything behind a darkness area would also be in the dark / shadow.

Unfortunately, the 15-foot-radius sphere is not said to be shrinking. If it were, we could imply that the light and darkness are annihilating each other up until the point were the darkness is gone.

Also, because of diffusion², whether a sphere of darkness would cast much of a shadow outdoor, I would say probably, but really not much. You could try with a d20 and see that the shadow is really not much unless you are really close to the ground. On the other hand, I would say that such a darkness sphere in a corridor totally blocks the light if the sphere fills the corridor.

Now... there is an interesting point, if you cast the darkness on an object such as a stick, you can then place an opaque object over that stick in order to block the darkness! Very similar to having a hooded lantern and closing the hood. Yet, a creature does not seem to be considered opaque enough to block the darkness...


¹ I think to remember that AD&D (1e) was clearly saying that all light was destroyed when entering the darkness area. Unfortunately, I do not have the books anymore.

² Note that diffusion really needs some form of material to work. I would think that Darkness can't be considered matter...

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    \$\begingroup\$ The bit about light spells being dispelled isn't anything about destroying light, it's because darkness spells and light spells are opposites and the game needs to say something about how they interact. \$\endgroup\$ Jan 23, 2015 at 17:16
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    \$\begingroup\$ +1 "A creature with darkvision can't see through this darkness" - so even electromagnetic radiation (including visible light) emitted or reflected by something on one side would not pass to the other - creating a shadow. \$\endgroup\$
    – Davo
    Jul 17, 2019 at 11:20
  • \$\begingroup\$ The darkness can in fact be illuminated. Faerie Fire at 3rd level can illuminate without dispelling it. \$\endgroup\$ May 19, 2020 at 8:34
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    \$\begingroup\$ @srcs You're confounding our space, which is mainly void, not darkness, with the effect of a darkness spell. Definitely not the same. Light can definitely pass through void. \$\endgroup\$ Apr 16, 2022 at 0:27
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    \$\begingroup\$ @srcs darkness in the real world is the absence of light. Magical Darkness as described in the spell is the destruction of light, not just the absence of it. Also consider, in the depths of space, there is light all around you....it may not be bright but it's there. In the middle of a darkness spell there is utterly no light at all, not even darkvision visible light. Consider it like being in a hermetically sealed orb. no light inside, no light behind it either....that's kinda the question here. \$\endgroup\$
    – Escoce
    Jul 29 at 20:30
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There are three things to consider here:

  1. D&D is not a physics simulation
  2. There are no hidden rules in D&D.
  3. The rules, especially RAW are only a tool to run a game

Other answers have covered what the laws say, and more importantly, what they don't say. They don't say anything about how magical darkness interacts with light passing through.

This means the "there are no hidden rules" rule apply here, so darkness doesn't cast shadows, case closed.

Except...that would in itself be a hidden rule.

The main problem is that while in the spell's description darkness is a thing that "spreads" and its spread can be blocked by covering its source with an obscure object, "casting a shadow" is not a real thing, it's simply another name for "blocking light".

And while D&D is not a physics simulation, the laws of logic still apply: either light can pass through or it can't pass through, there's no third option.

And if light passes through, an outside observer, while unable to see anything within the sphere of darkness, could see with perfect clarity what's on the other side.

And we've already got a name for that effect: invisibility.

Since there are no hidden rules in D&D, and there is no rule that says the contents of the sphere become invisible, the only remaining solution is that the sphere blocks outside light from passing through, i.e. "it casts a shadow".

But we've already "proven" that this also violates the "no hidden rule" rule, so how could that be then?

Well, the simple answer is: the description of magical darkness is broken. It's broken because you can deduce both that it casts shadows and that it doesn't.

And this is where assumption 3 steps in: the rules are there to help the game, not to break it.

Thankfully in this case the rules are very easy to fix: just bring magical darkness in line with magical silence. In comparison, here's what the Silence spell says:

For the duration, no sound can be created within or pass through a 20-foot-radius sphere centered on a point you choose within range.

There, nice and clear, and crucially, intuitive. Which is important if you prefer understanding the world you play in without a degree in law and formal logic.

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    \$\begingroup\$ Except...that would in itself be a hidden rule. Nice pun/play on words. \$\endgroup\$ Jul 31 at 18:24
  • \$\begingroup\$ excellent, my first....You're stupid for asking answer. \$\endgroup\$
    – Escoce
    Aug 8 at 2:35
  • \$\begingroup\$ @Escoce Apologies, it wasn't meant to be one. \$\endgroup\$
    – biziclop
    Aug 8 at 9:05
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Arguably, in 5e any kind of darkness casts a shadow

This is straight from the rules for darkness (p. 183, PHB), and is both unintuitive, and not how darkness behaves in the real world:

Darkness creates a heavily obscured area. Characters face darkness outdoors at night (even most moonlit nights), within the confines of an unlit dungeon or a subterranean vault, or in an area of magical darkness.

And, the definition of what a heavily obscured area does (same page):

A heavily obscured area—such as darkness, opaque fog, or dense foliage—blocks vision entirely. A creature in a heavily obscured area effectively suffers from the blinded condition (see appendix A).

So as per the rules, any kind of darkness, magical or not, is as impenetrable as fog or dense foliage, both of which throw shadows. The issue is not the sentence about effective blindness (which was even errataed, because the wording before could be read to have darkness actually give you the blinded condition), but that first sentence about "blocking" vision. This is so unintuitive that the games authors forgot about it in the DMG, when they mention seeing a light in the distance (DMG, p. 105):

Bright light in an environment of total darkness can be visible for miles, though a clear line of sight over such a distance is rare underground.

It would be a lot more useful to read this in a way to reconcile the two passages, and say you cannot see anything in darkness, but can see things in light areas from darkness. That definition unfortunately is not the one we got, but it would mean darkness, magical or not, would not cast a shadow. (As discussed here, you alternatively could decide to treat normal darkness like that, and magical darkness like a black fog, in which case again, magical darkness would cast a shadow).

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  • \$\begingroup\$ It could be that the descriptions of darkness in the PHB and DMG are at odds, because the first description had been forgotten when writing the second. Or it could be that they actually are the same, because of what being 'effectively blinded' means. A truly blinded creature can't see at all. But an effectively blinded creature (I would argue) can't see within the area that is heavily obscured even though they can see normally outside this area. This allowance means that the DMG still makes sense when it says that normal light can penetrate normal darkness...(1/2) \$\endgroup\$
    – Kirt
    Jul 29 at 22:43
  • \$\begingroup\$ (2/2) It also permits the PHB to make sense in saying that a moonlit night outdoors is under darkness, because how could the night be moonlit if one could not see the light of the moon penetrating the darkness in which one was? Given that this small allowance unifies both definitions and helps me make sense of how to rule on darkness, I find it more useful than saying the two definitions are different, but the correct one is the nonsensical PHB version. \$\endgroup\$
    – Kirt
    Jul 29 at 22:45
  • \$\begingroup\$ @KirtnoQA4mewhilemodsstrike I think the issue is not the sentence about blinded but the one about "blocks vision entirely". I agree strongly one should look fir a way to fix this with another reading; I’ll add something. \$\endgroup\$ Jul 30 at 4:12
  • \$\begingroup\$ Yeah, that one is harder to justify. Best I could do would be to say a heavily obscured area blocks vision of the area entirely, but doesn't block vision outside or through the area. It is a heavily obscured area, after all, not a heavily obscuring area. \$\endgroup\$
    – Kirt
    Jul 30 at 4:41
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The very notion that it is a sphere of darkness (darkness that spreads to fill a sphere) assumes that light can't go through, otherwise the sphere itself would be transparent. It has to absorb light to appear as darkness. And obviously, if light can't pass through it, it casts a shadow.

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    \$\begingroup\$ While I like your logic, this answer would be improved by citing examples or specific (official) rules that led you to this conclusion \$\endgroup\$ Jul 19, 2019 at 5:14
  • \$\begingroup\$ Why do you think it's not transparent? \$\endgroup\$
    – srcs
    Apr 15, 2022 at 20:52
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The Darkness spell absolutely casts shadow.

Consider these options 1 and 2 with a character hiding inside the darkness:

  1. Light passes through it and no shadow is cast by the spell
  2. Light doesn't pass through and shadow is cast by the spell

1: If darkness didn't stop light from passing through, then the character inside the area would cast a shadow (and be seen as a shadow at least), unless the spell works like a cloaking device by wrapping light around it. In that case the area wouldn't be seen dark, but translucent, and there is actually another spell that have this kind of effect and it's called invisibility.

2: The spell creates a 15-foot sphere, which no light can pass (except high level magical one). The area would look like total darkness to the eyes and it would also cast shadows, because it blocks light. The character inside the sphere can not be seen (or see, unless they have Devil's sight).

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    \$\begingroup\$ There's a 3rd option: Darkness looks like a black sphere when you look at it (imagine painting it on a photograph of a scene) and behaves as if its insides were invisible (except to those with Devil's Sight), so shadows don't reveal what is inside it. \$\endgroup\$ Feb 22, 2021 at 19:00
  • \$\begingroup\$ Darkness is not a wall or a fog. You can see a torch in the distance in a dark cavern. \$\endgroup\$
    – srcs
    Apr 15, 2022 at 20:51
  • \$\begingroup\$ @srcs You can see a torch through mundane darkness. The question is about magical darkness. \$\endgroup\$
    – Kirt
    Jul 31 at 15:59

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