Sweeping Up the Wilderness

Horse-Drawn McCormick Mower

Last week I opened my personal journal on accepting sweep attacks (fighters getting as many attacks as levels vs. 1 HD targets) as a critical element throughout the O/AD&D rules, and my own game, and the effect they have on play. Today we revisit our analysis of wilderness encounter perils, in the context of including sweep attacks in the picture.

State of the Wilderness

Here's a recap. Back in 2019 I analyzed Wilderness Encounter Levels, and the overall distribution of danger on the OD&D outdoors tables. A first observation is that, on average, the different terrain types are actually pretty uniformly dangerous: we estimate they're roughly balanced for a 10th-level party (with a classically big size of 8 PCs, fighters only, and no sweep attacks). A second observation is that looking past the averages, the encounters have a very prickly distribution: lots of encounters at total 50 EHD or less; but also lots of encounters with EHDs in the 200s or higher. (EHD being "Equivalent Hit Dice", something a bit analogous to challenge ratings.)

In 2020, considering that problematic, I took a stab at considering Rescaling Wilderness Encounters; maybe dialing down some monster numbers to get things a bit more manageable -- possibly by Arneson's tactic in the First Fantasy Campaign (assume only about a third of any group is wandering outside the lair), or Moldvay's in the Basic D&D rules (drop humanoid numbers to around one-sixth the original). Here's a copy of the table I had there of EHD distributions for all encounters in the OD&D wilderness (note the logarithmic x-axis):

Frequency of Encounter EHDs
Now, as a statistician, you kind of hate to see that kind of bimodal shape in a graph -- the fact that there's not one but two upward spikes in totally different locations. (As noted: a whole bunch of encounters around 50 EHD total, and another big batch of upward of 500 EHD. The coin-flip of doom!) That usually suggests that you've got a problem with your polling process, in that you've likely munged together two totally different categories of things, and instead should be dis-aggregating and measuring them separately.

In this case, the distinction is easy to determine: the big batch of super-high EHD encounters is precisely all of the humanoid bands appearing in numbers of hundreds (men, goblins, orcs, dwarves, elves, etc.). All of those kinds of encounters have average EHDs of 150 to 300 or so -- whereas the median for the overall set is only about 40. Likewise, the wilderness encounter subtables that have lots of these types (Men and Giant-types, i.e., humanoids) have average EHDs of 120 to 200, while all other subtables (Lycanthropes, Undead, Dragons, etc.) only have average EHDs of 25 to 50.

Earlier in 2021, I looked at Monster Numbers Through the Ages, specifically for the canonical wilderness encounters, and considered them in relation to the status of sweep attacks in each of those editions. A discovery there is that in some ways the numbers were pretty consistent from 0E to 3E, and then disappeared from monster stat blocks after that.

Start Sweeping

So recently I added a switch to turn on sweep attacks in the Arena Simulator on GitHub, and last week I presented that it has the effect of reducing the effective power of 1-HD humanoids to about one-fourth their actual hit dice (on average; and of course this varies enormously by the exact level of classed fighter-type they're facing off against). At some point, I went to the wilderness data tables from before, and dropped in those modified numbers. Here's what the distribution of encounter EHD totals looks like now:

Frequency of Encounter EHDs (with sweeps)
So: In one fell sweep, that solves the problem. The bimodal shape is gone, and now it kind of looks like a normal curve (after logarithmic scaling).

Some more details: The overall median is still around 40 EHD; but now the bands of humanoids have average EHDs in the range of 30 to 70 or so, that is, a much better match. Likewise, the subtable statistics become less jagged; mostly in the range of 30 to 50 on average (in other words, fairly spread around that 40 median). More on that later.

The difference in those two graphs is pretty much what single-handedly convinced me that if you're going to play an O/AD&D style, all other things being equal (like numbers appearing for humanoids), then it's pretty much a necessity to honor the classic sweep-attack rule.

Stones in the Field

But there are still a few exceptions: outlier encounters that have total EHD way outside the standard range of about 30 to 70. These are four specific cases that fall neatly into two classes:

  • Creatures with summoning abilities. When these creatures are encountered, they can summon other allies to help them, multiplying their strength (vs. their book hit dice, if that's all you were looking at when balancing the encounter size). With the summons respectively doubling or tripling their power, the average total EHD for Vampires is 140, and for Treants it's 360.

  • Creatures with 1 HD but a 2HD subtype. There are two humanoids with 2 HD, but are sub-types of a 1 HD primary creature class. Therefore they share the same high number appearing as the main type in the table (some hundreds), even though they're outside the range given for the sweep-attack rule. The average encounter EHD for Gnolls is 220, and for Cavemen about 310.

Let's be a little more specific about that latter category: In the OD&D Monster Reference Table, Hobgoblins and Gnolls share a single line jointly. The have the same AC, movement, % in-lair, treasure, and number appearing (20-200). But the hit dice entry says "1+1/2", i.e., Hobgoblins have HD 1+1, and Gnolls have 2. So while I'd interpret Hobgoblins as being in the range for sweep attacks, Gnolls would be out. In that regard, giving them the same numbers appearing seems to be a big mistake. This kind of gluing-together of types is in the tradition of Chainmail, where a lot of monsters were presented as tiny alterations of other classes. (In the past I've mistakenly said Gnolls were 1+1 hit dice in early drafts of D&D, but it turns out that was a typo in the later derived document called the Dalluhn Manuscript, so let's ignore I ever said that.)

Meanwhile, Cavemen don't appear in the table, rather being subsumed by Men, who have number appearing 30-300 and generally 1 hit die/man. But among the 9 different sub-types of Men described in the main text, Cavemen are uniquely noted as having 2 Hit Dice. (Actually, in the pre-publication draft of D&D, even that was ambiguous: the Guidon D&D manuscript says they "fight as 2nd level Fighting-Men", which could be interpreted a few different ways; when the LBBs were published, the entry was expanded to also say they "get 2 Hit Dice", apparently in response to some peoples' confusion. Thanks to Jon Peterson for personally answering a question about that.) Again, with this clarification, Cavemen stand outside the range of sweep attacks, but they still share the 30-300 number appearing like any other Men. 

Recall that up above I mentioned with sweep attacks, most of the wilderness subtables had average EHDs of 30 to 50. But I should point out that there's two notable exceptions: The Men (Mountains) and Giant subtables are both elevated up to around 90 instead, and that's entirely because those are the only tables with Cavemen and Gnolls (plus Treants) in them.

(Now, one might theorize that's evidence that 2 HD creatures should be in the range of sweep attacks, too. But there's even even more monsters on the reference table with 2 HD that have small numbers appearing: e.g., Zombies, Ghouls, Dryads, Pegasi. If we allow sweeps on them, then their EHDs plummet below the normal range, and you have an even worse problem. Also: most Horses and Mules are at the 2 HD level, and allowing whirlwind-slaughterhouse attacks against them just doesn't feel cool to me.)

So I do think that the numbers appearing in the four outlier cases are oversights and should be fixed. For Cavemen and Gnolls, following the idioms on the OD&D monster table, I'd recommend making their numbers 3-30 (as for skeletons/zombies), or 3-36 if you want to use Platonic dice, which of course you do, because you're a person of excellent taste.

Meanwhile for Vampires and Treants, I'd recommend lowering both to the smallest-appearing die of 1d4. This places Treant encounters at an average of about 80 EHD (still one of the highest), and Vampires at around 100 EHD (thereby making them the #1 most dangerous wilderness encounter). I'd actually make Vampires 1d3 if it weren't for the fact that it appears nowhere in the original table. Either way, this solves the eccentric subtables and related problems.

Wilderness Encounter Levels

All told, here's our revised estimate for encounter levels in the OD&D wilderness. Again, this assumes an eight-person, all-fighter party. When we started, we estimated that the tables present, on average, a balanced encounter for 10th-level PCs (with a huge amount of dangerous variation). By merely flipping on the sweep-attacks switch, our estimate drops to one appropriate for 6th-level PCs (and quite a bit more predictability in the danger, even you're still dicing for exact numbers in each case). What a huge difference that one rule makes! 

In both cases, this danger level is pretty consistent across all terrain types. Furthermore, if you make the adjustments to the monster numbers for the outliers I mentioned above -- even though that's only four entries -- they're influential enough to further drop the estimate down to 5th-level PCs. And that's pretty darned close to what many of our intuitions say (e.g., from the D&D Expert set rules) about what level wilderness adventures should be happening at in the first place.

One of my favorite things in the world is when two apparent problems cancel each other out, in that they're actually the mutual solution to each other. And for me, what appeared to be the bizarrely wonky variable danger of the OD&D wilderness encounter tables, and the mystery of whether sweep-attacks for PC fighters were really intended within the OD&D mechanics, is just such a satisfying case.

Just One More Thing

So sweep-attacks are the solution to the specific problem of big humanoid numbers in the wilderness. And yet separately, I'm still somewhat sympathetic to Arneson's idea in the FFC of having only around one-third of the given numbers actually show up wandering around in the wilderness (with the rest holding down the fort, or lair) -- applied universally to all monster types, not just humanoids. In some ways that cools the numbers for mythic monsters down to something more in line with what I have in my head for fantasy tales (what feels better: 4 dragons, or unicorns, or 1? 6 balrogs or 2? 8 giants or 3? 12 pegasi or 4?). And it also adjusts for the smaller standard (non-convention?) party sizes we might be dealing with now. If you reduce monster numbers appearing to 1/3 listed, and party size to 4 (instead of 8), then the average wilderness encounter in OD&D in fact seems to be balanced for 4th level PCs (exactly in line with the Expert rules expectation).

Appreciate any of your thoughts on that!

Wilderness Wandering Analysis 1.0.3 (ODS spreadsheet)


  1. I had the thought that perhaps "1+1/2" could be read as not 2 HD for gnolls, but 1+2 HD for them instead, which would bring them back into the realm of "normal men." Of course, this could be contradicted elsewhere, but I think it could be a fair interpretation of the table entry at least

    1. I'm totally with you. In fact, I think even if the text directly contradicts it (as with Cavemen), that's the correct solution.

    2. We kicked this around a bit on the WDMs Discord server. Me, I'm leaning to the intent really being 2 HD.

      It's reminiscent of a typo that crept into the skeletons/zombies line in later printings of OD&D. Initially "1/2", someone later modified that to "½/1", but all the eldest hands swear zombies were always 2 HD in play.

  2. ---Appreciate any of your thoughts on that!

    Given the Arnesonian precedent, and that reality of smaller parties in modern gaming, I support the 1/3rding idea.

    1. Yeah, in many ways that feels nice. Although it's an extra step of math that I'd prefer wasn't needed working from the original tables (thanks, Dave).

  3. As we've discussed, I advocate reading Gnolls and Cavemen as 1+2, not 2. For one thing, if Cavemen fight as a 2nd Level Fighting Man, they should be using the 1-3 column on the men attacking table, which is 2 points worse than the 2 HD monster column all the way down. For another, that seems to me a smaller change than slicing the number appearing down.

    As for Treants, as I read the entry they can cause trees to move up to 3" but I wouldn't interpret that as making them able to attack.

    1. Also if you if you round the average 5.5 HP to 6, that's within a point of the 2 HD average. That really seems close enough to me to the implication of the entry for Cavemen as being like 2nd level Fighting Men but needing two hits (or one really good one) to kill.

    2. It's an interesting interpretation. Admittedly that sense of the slash in that column would be unique; the other places it's used indicate distinct hit dice (e.g., goblins/kobolds, skeletons/zombies).

      And also interesting interpretation on the Treant control ability. In both Chainmail and AD&D, it's explicit the controlled trees can fight like treants at the 3" move rate, so nowadays I take that kind of before & after pattern as conclusive. (Does that happen in LOTR?)

    3. In LotR, as I recall, the Huorns (animated trees) are understood to kill the orcs which flee into them, as they cut off retreat from the battle of Helm's Deep.

    4. Yes, but as I understand it the Huorn aren't just trees. They can move and attack on their own, not just under the influence of Ents. But you're probably right the intent is that the trees fight like Treants. In that case, though I'd fall back on "Treants are not prone to involve themselves in affairs which do not directly concern them" as a reason not to worry so much about their difficulty spike.

    5. That's within reason. Also that super-slow movement is not something the simulator really handles (it just assumes everyone's in melee).

    6. Follow-up with contrasting before/after case: Chainmail says Lycanthropes (which are Bears or Wolves) bring animals that double their fighting numbers (in woods). But the OD&D LBBs don't say that, and in AD&D Bears get an ability of that type, but Wolves don't. (Meanwhile Rats in Sup-I and AD&D have a summoning ability.) So that's a lot sketchier to me.

  4. Numbers 3-30 can be found with platonic dice. Remember; the original d20's were numbered 0-9. They could be used for d10's. Just saying. Great study!

  5. Very satisfying indeed!
    Your simulations continue to amaze. An innocent question (not entitlement): Does your simulator account for morale? That should drive up the EHD of undead and possibly drop that of weak humanoids...

    1. Good question, that it does not. Part of the problem there is that there's no core method in classic D&D for morale: Vol-1 p. 13 suggests one could either look at Chainmail (which itself has two different methods), or use the Reaction table in some way (which would need fleshing out). Even with some elder players at the Gygax/Arneson tables, I've seen them have customize and make ad-hoc comparisons using the Chainmail tables. And B/X has a different thing, and AD&D yet another. So the interpretations for that would by flying in at least a half-dozen directions and almost no one would be happy.

      So the simulator for the EHD metrics is purely a fight to the finish, which I think gauges actual maximum potential threat. At the table one could let that inform whatever morale rules are in play. Thanks for the kind words!

  6. Good point. I totally forgot that there's no uniform approach, putting this into house rule or edition wars territory.

  7. Definitely necessary in AD&D for fighters to chop down lots of <1 HD types I have always found.

  8. Don't see any reason why cavemen wouldn't be 'normal men' as such, either, in the bandit/brigand sense.