A game master told me that moonless nights swallow dim light, and also turn bright light into dim light as well. My game master claims this rule is in the books.

Is this correct, by the rules as written?

I'm trying to find out if a moonless night (non-magical) would cause dim light to become darkness, and bright light (e.g. coming from torches) to become dim light (and that kind of stuff).

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    – V2Blast
    Aug 4, 2019 at 4:36

2 Answers 2


Absence of one light source does not affect the brightness of another

The brightness of a torch is not contingent on overlapping its light with some background light source, such as moonlight. This is evident from the fact that a torch works just as well underground in a pitch dark cavern (where there is certainly no moonlight) as in a moonlit (or non-moonlit) night on the surface.

Furthermore, moonlight is normally already considered darkness, as spelled out in the description of darkness in the Vision and Light section of the rules (emphasis added):

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.

So there is generally no mechanical difference between a moonlit night and a moonless night anyway.

I can't find anything in the rules that explicitly spells out how lighting from multiple light sources combines, but the most logical rule I can think of is: the brightest light source prevails. That is, if a object is illuminated by both a bright light and a dim light, that object is brightly lit. If another object is illuminated by two sources of dim light, it is dimly lit.

However, your DM can make new rules

Despite the above, the DM can implement any rules they like. It's possible that the "nonmagical" darkness of this moonless night is just a different kind of magic. The Sage Advice Compendium explains:

You might be thinking, "Dragons seem pretty magical to me." And yes, they are extraordinary! Their description even says they’re magical. But our game makes a distinction between two types of magic:

  • the background magic that is part of the D&D multiverse’s physics and the physiology of many D&D creatures
  • the concentrated magical energy that is contained in a magic item or channeled to create a spell or other focused magical effect

In D&D, the first type of magic is part of nature. It is no more dispellable than the wind. A monster like a dragon exists because of that magic-enhanced nature. The second type of magic is what the rules are concerned about. When a rule refers to something being magical, it’s referring to that second type.

Given this, it would not be unreasonable for the DM to decide that in the world they are building, the darkness of a night with no moonlight is not a mere absence of light, but in addition it has a slight supernatural edge to it that makes all light a little bit dimmer. This would be especially appropriate in a horror-themed campaign.

  • \$\begingroup\$ Thanks. The DM was claiming that a moonless outdoor environment would make the items light less, taking off the dim light and turning the bright light in dim light. \$\endgroup\$
    – Rodrim
    Aug 4, 2019 at 0:52
  • 1
    \$\begingroup\$ I'd like to draw attention to the word most in the sentence "even most moonlit nights". So some moonlit nights aren't darkness. I guess rest if left for the DM to decide, but it's still there. \$\endgroup\$ Aug 4, 2019 at 13:33
  • \$\begingroup\$ @WakiNadiVellir That's why I said "generally" and not "always". \$\endgroup\$ Aug 4, 2019 at 22:57
  • \$\begingroup\$ Well, you could also say it the other way around: only the brightest moonlit nights are not considered darkness. These do occur "normally" and somewhat predictably (or not, depending on local climate, ie. frequency of clear cloudless nights). \$\endgroup\$ Aug 5, 2019 at 7:47

In my experience, no rule ever tackled the specifics of moonlight vs torchlight

But, speaking from experience from spending a lot of time in the wilds, where one cannot rely on electricity, that both light sources are different and this is a tricky question.

Moonlight illuminates everything from far above

On a clear night sky with nothing to hide the moonlight, it is enough light to enable someone to jog on a narrow forest path without smacking your face in a tree every step (but one should still be careful, as you don't necessarily see the branches who could smack you in the face).

I've had to make such a run once, 2 miles in total darkness (only moonlight) helping an injured friend reach town on a camping trip, in a dense forest with no light (we were dumb, and didn't bring one).

Torchlight is a brighter light source

I've never actually walked with a torch as D&D adventurers do, but I often walked in the wilds at night with a flash light. After 30 seconds of looking at the ground with a flashlight, your eyes adjust to the brightness and the moonlight becomes irrelevant ... you cannot see further than the radius of your torchlight after a minute or two.

What does this mean for D&D?

It means there are no definitive rules and whatever a D&D DM chooses to do, you should roll with it.

But I personally would say, from actual RL experience, that a torch allows you to see small details better in a 15-30 foot radius than moonlight would allow, but it restricts your vision to that halo of bright light. Under torchlight, spotting something 100 feet away becomes impossible since your eyes have adjusted to bright light and your vision is restricted to the radius ... while under moonlight, you see farther but it is harder to make out the details of the path you are walking and any kind of "fine detail" that a brighter source of light would reveal.

  • \$\begingroup\$ Thanks for the answer, but I wanted to know if there was any rule defining that a darkness coming from a moonless night (non-magical) would take off a dim light and turn brigh lights in dim lights. \$\endgroup\$
    – Rodrim
    Aug 3, 2019 at 23:51
  • \$\begingroup\$ A torch providing bright light in a 20-foot radius and dim light for an additional 20 feet would be able to light it all into a moonless night darkness (non-magical)? Or just 20 feet dim light in this moonless night darkness (non-magical)? \$\endgroup\$
    – Rodrim
    Aug 3, 2019 at 23:59
  • 1
    \$\begingroup\$ The rules do say that "a particularly brilliant full moon might bathe the land in dim light" while a torch produces bright light, so a torch is unambiguously brighter than moonlight within 30 feet. \$\endgroup\$ Aug 4, 2019 at 0:09
  • \$\begingroup\$ Well, my question is if a torch will have 20 feet of a bright light and 20 feet of a dim light within a darkness witout a moon to illuminate or another light source. \$\endgroup\$
    – Rodrim
    Aug 4, 2019 at 0:30
  • \$\begingroup\$ @RyanThompson do you have an actual reference for that ? It does make sense, I did not remember the rules being specific about it. \$\endgroup\$
    – Catar4
    Aug 4, 2019 at 1:32

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