Subterrane Surveys: Caves of Chaos

This week we're looking at possibly the most-played of all D&D modules, Gary Gygax's Dungeon Module B2: The Keep on The Borderland (1980). Of course, we're not so interested in the Keep as the nearby, humanoid-infested adventure area, the Caves of Chaos. Bear in mind that this was the third adventure-supplement to be included in versions of the Holmes Basic D&D set (previously including the Dungeon Geomorphs, and later Mike Carr's Module B1: In Search of the Unknown). A smart move by Gygax, granted that the Basic D&D set had surprisingly become TSR's top seller (S. Applecline cites an estimate of some 1.5 million copies of module B2 being produced). That said, there is evidence that B2 was originally drafted using OD&D rules for hit dice.

Design: The adventure site here has a markedly different design from Gygax's early Castle Greyhawk or Dungeon Geomorphs mapping style. The map has a lot of negative space (it's not fully-packed with navigable space as are his earlier top-level maps). It has 11 different identified "cave" complexes, each with their own entry point from the central outside ravine. The cave complexes average about 6 keyed areas each (range between 1 and 14). Most are inhabited by a single humanoid type; and most have a secret entrance connecting to one other cave complex.

The stocking in most cases follows a regular pattern; given 6 standard areas, there are usually something like 2 guard rooms, 1 common room, 1 chief's room, and 2 "other" (like a storeroom, banquet area, slave pen, etc.). Usually the chief in each case guards the large treasure cache.

At this point, Gygax seems to have finally abandoned the early ideology that the majority of rooms in a dungeon should be empty of any contents. In fact, none of the 64 keyed entries are entirely empty of contents. Related, he no longer uses duplicated area codes for multiple areas (every space is unique). The vast majority of rooms have monsters in them: 57/64 (89% occupancy rate), very different from his earlier guidelines and dungeons that have only 20% or 33% occupied. (And consider how many more eyes saw this product as exemplary, versus those earlier rules.)

Characters: Under "Notes for the Dungeon Master" on p. 2, Gygax says: "This module has been designed to allow six to nine player characters of first level to play out many adventures, generally working up to second or third level of experience in the process." I think this may mark the first time that, in addition to explicitly stating a standard party size, an adventure also gives an expected progression rate upon completing the module. While 6-9 player characters may seem large by modern standards, consider that it still roughly matches normal convention-game sizes. I'll assume that a group is adventuring with around 8 total PC levels (same as expected for Carr's Module B1).

Monsters: As stated above, most rooms have monsters in them, with 57 total creature encounters in the place. In contrast to earlier adventures (Gygax's Castle Greyhawk, or Mike Carr's B1), the monster numbers here are all fixed specific quantities, not given as ranges. In the table above I've organized statistics for each separate cave complex. Most of the caves have a median encounter strength of 4, 5, or 6 EHD (Equivalent Hit Dice). There are three complexes that have about double that median encounter strength, i.e., 9, 11, or 12 EHD (caves H, J, and K). The module does not identify distinct "levels" to the Caves of Chaos, but we might hypothesize that caves H, J, and K are "2nd level", with the rest all being "1st level". If so, then a group of 8 PCs should generally be able to handle the average threats therein.

But one thing to note is that in many cases the "common area" of a cave complex has a very large number of monsters, presenting an outlier area of possibly extreme danger. For example, the kobold complex (cave A) has a median encounter of EHD 5, but the common chamber (room 6) has 40 adult kobolds all of whom will fight, for a total EHD of 26 by my estimation. Likewise the common rooms for the hobgoblins, bugbears, and gnolls have total EHD of 2 or 3 times the nearby guard rooms; and the evil shrine area has a median EHD of 12 but one area with a veritable army of undead, for a total of EHD 60. Keep in mind that all of these creatures have every reason to spill forth and attack if an alarm is generally raised; and the humanoid common areas would likely have to be entirely filled with bedding from wall to wall to house the indicated numbers. Possibly if PCs fight smart and bottle up the numbers with an organized front line in the narrow passages, then these encounters would be more manageable than the raw numbers indicate.

What about wandering monsters? The text of the module never explicitly says. On the one hand, there is a tear-out rules summary sheet in the center that duplicates the wandering monster lists for levels 1, 2, and 3 (originally as per the Holmes published text, the tables therein created by Gygax; in a later edition the Moldvay B/X tables were inserted instead). We might use the 1st/2nd level classification I suggested above. If so, Gygax's tables in Holmes have an average EHD of 4 at 1st level, and 8 at 2nd level; so they would be only slightly less strong than the set encounter areas. But on the other hand, two of the caves are noted with specific roving guard groups who attack intruders who make a commotion (goblins in cave D, zombies in cave K), so the expectation for wandering monsters is not entirely clear.

Compared to the previous module B1, module B2 is much more densely packed with monsters. B1 had an average EHD of 4 throughout (both levels), and an occupancy rate of only about 32%. In contrast, B2 has median encounters of between 5 and 12 (depending on cave complex), some very highly-populated monster lairs, and an occupancy rate of 89%. In total, B1 will have about 72 EHD of monsters, while B2 has 464 EHD, over 6 times the monster threat. As I've stated before, you can adventure in B1 quite successfully with around 4 total PC levels, but you shouldn't dare try that same thing in B2.

Treasures: Almost all of the areas with monsters also have some kind of treasure; specifically, 49/57 (86% ratio). Gygax is clearly customizing treasures, i.e., not using the book rules, because coin values come in odd values to the units-place, like 76, 139, and 157 (not round 10's, 100's, or 1000's in the various book tables). Moreover, almost every single humanoid is given a small amount of personal treasure, like 1d6 or 2d6 copper, silver, or gold coins. Frankly, this was one of the more frustrating things about analyzing this module, as it took quite a bit of calculator-work on my part to compute expected coinage from all these die-rolls in these scores of areas. In some sense you can understand the gesture of "Gygaxian naturalism" to have many scattered odd-amounts of personal coins, but in many cases the total value is negligible (like 2, 5, or 10gp total in an area), and I think it may detract from the game to have to roll, sum, and document these many weird small numbers.

Note that in OD&D Vol-2, men (and only men) are given this kind of small individual treasure, per the footnote to Treasure Type A (p. 23). In later rules Gygax expanded this to many different types of monsters; the first debut of the idea was when he struck out the old Treasure Types table in the Holmes Basic D&D draft and replaced it with an extended table with various small individual types -- even though none of the monsters in that work used them (see here). This same table was expanded a bit more, and more comprehensively used, in the AD&D Monster Manual. B2 represents the first adventure where this is generally utilized throughout.

In almost every case the chief of a cave complex has a large, significant treasure hidden someplace in their room. I suppose we might argue about whether the small-personal coinage everywhere else should even be counted as a true treasure, but I have done so in the ratio above. Total treasure in the place adds up to 28,657 gp, about 8 times the amount in Greyhawk level 1 or both levels of B1 combined. While that's a much larger total haul of treasure, it's about 60 gp per monster EHD, still very close to the ratio we saw in both of those earlier works (but less than the Gygax-edited Dungeon of Zenopus with a ratio of 100, to say nothing of Holmes' hyper-inflated draft valuation of 500 gp per EHD).

Magic: In addition to every chief having a large treasure, they almost always one or two magic items, as well. (The evil shrine has an even larger proportion of magic.) There are 13 treasures with one or more magic items out of 49 total treasures (27% rate). This is very similar to the ratio in Mike Carr's B1, but less than the earlier Holmes or Greyhawk dungeons (which had rates around 50%).

Experience: As usual I'll ignore wandering monsters (of which there is some ambiguity, above) for this purpose. If we use the Greyhawk-style revised XP awards that appears in Holmes Basic D&D, then total XP from all monsters adds up to about 5,500, and treasures add up to 29,000 or so, for a grand total of about 34,500. The monster: treasure ratio is about 1:5 (16% to 84%). The total is indeed a bit more than enough to promote 8 fighters from 1st to 3rd level, as asserted in the introductory material to the module (see "Characters" above).

Compare to using the Original D&D Vol-1 XP awards where we give a higher, flat 100 XP per EHD. Then, given the incredibly large number of monsters herein, we get 46,400 XP from monsters, added to the 29,000 for treasure, for a total of 75,400 XP. This would be a monster: treasure ratio of about 3:2 (62% to 38%), and the total would actually be enough to promote 8 1st level fighters to 4th level, exceeding the expectation on the 2nd page.The overall lesson is that compared to earlier dungeons, the Caves of Chaos are much more densely packed with content; almost every room is veritably bursting with monsters and oodles of treasure.