Wandering Monster Levels

This is the first in a series of posts on the math behind the presumed dungeon-monster ecology in OD&D. Specifically, we'll be looking at the various Wandering Monster tables and figures presented in OD&D Vol-3, p. 10-11. Interestingly, there's significant evidence that these tables came out of particular Greyhawk Castle play (thereby being representative of that specific setting), whereas later publications moved in a direction of greater generality.

In each edition of D&D, there have been tables for Wandering Monsters, and they're often dual-purposed for such things as random dungeon stocking, etc. Before these tables are accessed, there is something like a "Monster Level Matrix", which I'll look at here; consider the versions in Holmes, OD&D, and AD&D (in order of increasing complexity):


Now, what I've done here is not directly transcribe the tables themselves, but rather convert them to frequency statistics (i.e., showing which possibilities are most likely; OD&D rolls 1d6, Holmes 1d12, and AD&D 1d20).

Holmes has about what you would expect. In each dungeon level, the equivalent level of monster is most common; the others are sequentially less likely, or, at 2nd level, they're equally split between small numbers of 1st & 3rd-level monsters. Simple.

Now look at the Original D&D tables. They're tough, man. At 1st level, the possibilities are even between 1st & 2nd level monsters. On the 2nd dungeon level, the most likely encounter is already 3rd-level monsters! (For example: Wights, ochre jelly, giant snakes, 4th-5th level fighters, 5th-6th level magic-users.) By the 3rd dungeon level, 4th-level monsters predominate (Including: Wraiths, giant scorpions, lycanthropes, gargoyles, white apes, 6th level fighters, 7th level magic-users). Notice how many of these require magic weapons to hit, or have energy drain or poison abilities, or are just generally very tough at this level.

I think I can come out and just directly say that this OD&D table was pretty much in error and not terribly well thought out. It just gets excessively tough really quickly; there's no balanced place for 2nd-level PCs to explore, for example.

Now let's look at Gygax's follow-up with the AD&D tables (stretched out from 6 to now 10 levels of monsters). Here, the 1st-level monsters are most likely at both the 1st dungeon level, and also the 2-3rd dungeon level category. Not until the 4th dungeon level are 3rd-level monsters more common than others -- and that's still the case at the 5th dungeon level. Rather oddly, low-level monsters continue to appear at every possible level of the dungeon. Clearly the advancing deadliness has been much toned down compared to OD&D. (Still, 2nd-level monsters fail to be most common at any level. And why are dungeon levels 2-3 singularly merged? Possibly an overreaction to the 2nd level jump in OD&D?)

I think this is a case where Holmes presents a reasonable, happy medium, one that seemed to escape Gygax as he veered from too-deadly in OD&D to somewhat too-fiddly and forgiving in AD&D. My personal preference would be an OD&D-style table (based on d6 and 6 levels of monster) that had a more regulated increase in risk level.