Is there a standard or default frequency for wandering monster checks in an underground dungeon?

This concerns both dungeons of my own design, and existing modules either by TSR or Judges Guild that do not specify an encounter frequency for the dungeon.

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    \$\begingroup\$ Yes, I really am playing the ‘77 edition, hence the tag. There are three books in question and if you’ve read them you’d know they’re not known for their stellar organization. \$\endgroup\$
    – munk
    Jul 20, 2019 at 21:30
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    \$\begingroup\$ Having spent the last few hours off and on trying and failing to track this down, I'm pretty eager to see an answer. \$\endgroup\$ Jul 21, 2019 at 0:26
  • \$\begingroup\$ @SevenSidedDie I think I've found it (but it relies on OD&D also ...) \$\endgroup\$ Jul 21, 2019 at 0:37
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    \$\begingroup\$ @Mołot Ah. The phrasing you used before came off to native speakers as rhetorical, disbelieving, and vaguely accusatory (“Are you really…?”). I’m not sure how easy that is to detect from outside the native speaker population, because it’s very contextual. A safer phrasing next time might be “Can you confirm your question is about…?” since it’s directed at the question rather than the person, and it’s less casual phrasing. \$\endgroup\$ Jul 21, 2019 at 17:39
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    \$\begingroup\$ @Mołot The part that bothered me the most was “what does the book say?” That came across as an accusation that I had not made the effort to read the rules. But I’d like to point out that questions about rules and mechanics are on topic here. I’m having a hard time framing that as bad phrasing. Maybe give the asker a little more credit in the future. \$\endgroup\$
    – munk
    Jul 21, 2019 at 18:17

1 Answer 1


Every three turns, unless the DM decides otherwise

This answer presumes that the only material you are using as a reference are the PHB, MM and DMG.

  • If you also have the Holmes Basic Dungeons and Dragons book (which was published as a precursor to AD&D as the game evolved) the answer is in that tome.

How did I come up with that answer from the DMG? (I hear people wonder) The 1e DMG is, as you pointed out in a comment, organized in a counter-intuitive fashion.

You'll find under City encounters the following text.

Check for encounters every three turns as normally, or otherwise as desired. (p. 190)

Where was the 'normally' covered? Nowhere in the AD&D three core books1, though "once per turn" was "normally" for the original game (see below). It is in the Holmes Basic set, which was meant to be a stepping stone to AD&D:

At the end of each three turns the Dungeon Master can roll a die to see if a wandering monster has come down the corridor. A roll of 6 means that "something" has come strolling along. (Holmes, p. 10)

If one didn't get the Holmes Basic Set before getting AD&D, one can be excused for not knowing what the "normally" referred to.

Walking back to 'keeping track of time' in the DMG we find:

It is essential that an accurate time record be kept so that the DM can determine when to check for wandering monsters, and in order to keep a strict check on the duration of some spells ... On occasion a party may wish to hole up for a long period perhaps over night ... this does not exempt them from occasional checks for wandering monsters, though the frequency may be moderated somewhat, depending on conditions ...

Maddeningly, for those looking for a concrete answer, a periodicity was implied ...

When a random encounter is indicated by the periodic check ... (p. 174)

... but there isn't a hard and fast rule in that section on random monsters, and it refers you to your own table/chart in that passage as well. While that implies that you may be best served by making your own chart and periodicity, it does not require it.

Unless the DM says otherwise ....

The 1e AD&D DMG does not give you a hard and fast rule. Don't let that be an obstacle to play. Throughout the 1e AD&D DMG, the author expends a significant amount of text providing guidance to the DM. I'll distill into a simple principle: do as you will, you are the DM.

And it works (the DM arriving at their own rolling frequency). Well, it worked for me for some years when I was running and playing in AD&D 1e dungeons.

An example of when the DMG suggests more frequent checking:

If wooded doors are broken down by axes and the like, it will take some time -- a full turn {ten minutes} is usual -- and require at least 3 checks to see if nearby and / or wandering monsters are attracted by the noise. (p. 97, Doors)

You will note that this check includes both the wandering/random monsters, and any monsters you have already placed in that area of the dungeon that you expect to be able to hear a door being destroyed by ax blows. (The section on pages 96 through 100 give some interesting examples of how the author expected play to flow. It's worth another read ...)

Alternative Answer: Once per turn, roll a 1d6

A lot of AD&D was written with the core assumptions of playing Original D&D (three little books in a box, 1974) as an embedded assumption. In Volume III, Wilderness and Underworld Adventures, it says this:

Wandering Monsters: At the end of every turn the referee will roll a six-sided die and see if a wandering monster has been encountered. A roll of 6 indicates a wandering monster has appeared. (p. 10)


In the first five years that I played D&D and AD&D (1975-1981) that was "normal" in a lot of the dungeon crawls I participated in. The OD&D styles bled into AD&D in most cases. In play, the "unless the DM says otherwise" was as common as any predictable periodicity. We also saw some DMs make it "one check per hour" {one roll per six turns} but that may have just been local practice.

Using wandering monsters as a way to "move things along"

None of the above precludes using a check for random monsters whenever you feel that it is appropriate. With published adventures, some have a guide on the frequency of random monster checks, and some don't.

1 Every third turn became "normally" in the time between OD&D got published and the AD&D DMG got published, and was captured in Basic D&D(Holmes) as noted above. In the instructions to DMs in the In Search of the Unknown module that accompanied the Basic set's fourth and fifth printings (1979), Mike Carr gives this guidance to DM's:

Every third turn of adventuring, the DM should take a die roll for the possible appearance of wandering monsters at the indicated chances (which are normally 1 in 6, but which may vary depending upon location and dungeon level). Some occurrences (such as noise and commotion caused by adventurers) may necessitate additional checks. (p. 4)

Why do I bring this up? Mike Carr was the rules editor for the AD&D Dungeon Masters Guide (among other game products) and had played in both Arneson's and Gygax's home campaigns. He began working for TSR in 1976, and was there for the evolution of the game from OD&D (three books plus supplements) through Basic D&D (Holmes) to AD&D. The module was included with the fourth and fifth printing of the Holmes basic set in 1978 (published before the AD&D DMG while that tome was being completed). Part of its stated reason for inclusion was that it was "... especially designed as an instructional aid for beginning dungeon masters ..."

That module was not explicitly published for use with AD&D (though we ran it under AD&D with no problems) except that Basic D&D was supposed to lead the players and DMs to Advanced D&D if we are to believe what is written in the Holmes rule book.

Carr's point on "normally" being one check per three turns bears a striking parallel with the "normally" I mentioned from the AD&D DMG (Which he edited. My copy has him signing off as editor on page 2, 15 May, 1979). It also reflects what is in Holmes.

It's reasonable to believe that in the evolution from OD&D to AD&D, the Wilderness and Underworld Adventures "once per turn" became (in practice) "every third turn" and that this play-testing change came about in parallel with the development of the sequel editions of D&D once the "three little brown books" were overhauled and updated to account for the many changes that had taken place since their initial promulgation.

  • \$\begingroup\$ Falling back on OD&D and the classic 1 in 6 per turn is the conclusion I came to as well, with the same reasoning. \$\endgroup\$ Jul 21, 2019 at 4:08
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    \$\begingroup\$ @SevenSidedDie I had a number of DMs who would a use six sided die as a counter. It would start on the 1, and as turns went by the die would be rotated to show the next face. This was a way for us all to be aware of how many turns had gone by (the passage of time). Most of those DMs only rolled a random monster check when the die had completed an hour (6 turns), but I cannot remember where that technique originated (local idea someone had that had spread from group to group, perhaps). I was looking for that idea's origin also. I came up empty on anything other than memory. \$\endgroup\$ Jul 21, 2019 at 10:41
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    \$\begingroup\$ @SevenSidedDie Oh my, it appears to have come from Holmes/Basic D&D. I had to read through my copy twice to catch it. \$\endgroup\$ Jul 21, 2019 at 16:26

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