## 2010-08-16

### 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.

1. 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.

Yet another point in Holmes's favor. :)

2. there's no balanced place for 2nd-level PCs to explore
to be honest i think level 1 meant to be for characters of level 1 to 3, level 2 for characters 2-4 and so on.
And this is the only bit I don't agree on, thank you for the interesting post :)

3. Note that in AD&D, I believe that if you found an easy monster deep in the dungeon it came in larger quantities.

It actually works out great. At the upper levels of a dungeon, you find a handful of goblins. In the middle parts, you find large bands of goblins. In the depths, you find whole villages of goblins.

As I recall, it also works the other way around; if you find a tough monster in the shallow parts of the dungeon then the quantity is reduced.

4. 2nd level monsters are very few and far between in AD&D, so it's just not really possible to make them the theme of a level. This is because the categorisation of the monsters into levels doesn't assign enough range to 2nd level (30pts). It's easy to design weak monsters that come in at 20xp or less, and 3rd level's 51-150 is a nice wide target to aim at, but 21-50 is tricky when 2HD gives an average xp of 38 right off the bat.

War dogs are 2nd level as are the giant frogs.

One additional question is the numbers appearing per level. It's not actually totally clear in AD&D how many orcs, for example, the DM is expected to throw in on level 16 of a dungeon but it seems to be (1d6+6)x16, for an average of 168. That's going to be one of the bigger rooms!

The variation in xp value and challenge level of the AD&D random tables (especially level 1) is something that can cause great vexation in play.

5. @Vedron: "Note that in AD&D, I believe that if you found an easy monster deep in the dungeon it came in larger quantities..."

Yes, and that's true across all the versions of D&D that I'm looking at. See: OD&D Vol-1 p. 11, Holmes p. 10, AD&D DMG p. 174.

@Nagora: "It's not actually totally clear in AD&D how many orcs, for example, the DM is expected to throw in on level 16 of a dungeon but it seems to be (1d6+6)x16, for an average of 168. That's going to be one of the bigger rooms!"

Yes, and that's part of the failure I see in the AD&D system. Other editions, by cutting off the presence of low-level monsters at some point, avoid this awkwardness.

More specifically, the "Number Appearing" issue will be the subject of Friday's post. :)

6. @Nagora: "...an average of 168. That's going to be one of the bigger rooms!"

Oh, and of course the primary usage isn't even supposed to be in a room, i.e., "wandering" in a hallway.

7. @tsojcanth: "to be honest i think level 1 meant to be for characters of level 1 to 3, level 2 for characters 2-4 and so on."

Having thought about it, I think that might actually exacerbate the problem. That would mean there's only a x1.5 increase in PC strength (average level 2 vs. 3) whereas you're increasing monster strength by about x4 in my rough estimation (x2 per monster level, and 2 of those steps from dungeon level 1 to 2).

1. Actually, I think that's correct and maps nicely to the way I think the game was played early on.

1st level characters do not lightly go into 1st level dungeons, and the first levels of dungeons were large. 2nd level characters were more capable and 3rd level characters could potentially clear the level.

Repeat on level 2 of the dungeon.

After that, there's more linearity, but characters are much more powerful in terms of the manpower they can draw on, their henchmen are leveled to within a level of themselves and so on.

2. and burn me for not noticing the dates. feel free to ignore this. :P

3. Welcome and we consider it an ongoing discussion! :-)

8. @delta: but PCs and monsters don't scale linearly in strength raising in levels. In fact, except for casters and fighting men against low-level-goons, the progression is sublinear for average opponents (I don't want to do the math here). This is due to the fact that the damage dealt per round increases slowly, so the only significant increase after leveling is the hit points one.
This is valid in both directions obviously :)

9. @tsojcanth: "but PCs and monsters don't scale linearly in strength raising in levels."

Let's focus on PCs: That was my initial expectation too, until I did some tests and found out otherwise, to my surprise. (Admittedly that was for 3E: could be mistaken, but my assumption is it's also true for other versions.)

Consider AD&D style extra attacks, assumption of magic weapons, rising AC making one more unhittable to opponents of a given level. Even if you reject that, "except for casters and fighting men against low-level-goons" is a very wide swath of the sample space.

And since PCs are inserted in the monster tables at regular intervals, you have to assume monsters are similarly scaled, or the whole thing's just totally irrational.

10. @delta: 3E is a different beast as PCs rise in power much more. Under BECMI fighters get their second attack at level 12 AFAIK and in 3E at level six, less f dual-wielding. Damage throughput is way higher too due to specialization, better stat bonuses, better buffs, better availability of magic weapon, better chargen.

I'll churn out some BEC math later on today if i can round to sort the rest of my duties :)

11. @tsojcanth: I can respect the difference of opinion. I'd recommend you save the effort, as at this point I usually need a practical combat-simulator (with stated assumptions for magic gear, etc.; Monte Carlo-type method) to be statistically persuaded otherwise.

12. @delta: that was more or less the plan :P