Alternative Level of Monster Matrix

Tavis over at The Mule Abides sent me a question last week that reminded me of my OD&D monster level analysis blogs from last August (some key links below). I pointed out some oddities of the OD&D dungeon encounter tables at that time, and meant to present alternative options for them (with the usual smallest-possible changes), but never got around to it.

For example, on OD&D Vol-3, p. 10, you get the "Monster Determination and Level of Monster Matrix" (i.e., what level of monster do you encounter?). My observation from last year is that the table is tough: by the 2nd dungeon level, the average encounter is with a 3rd-level monster, with a good chance of getting a 4th or 5th level monster (and remember that the scale only goes up to 6!). That's probably too accelerated, and if you look at the AD&D DMG, Gygax would perhaps agree; he actually overcompensated in the other direction there, and made the equivalent table go up too slowly.

Here's what I currently use. It's not rocket science: simply make the progression smoothly increase. The average encounter level now increases by one for each row of the table. I also added a column on the far right called "tier" (i.e., index of the row; same as dungeon level for 1-4), which we'll use in a bit:

Alternative Level of Monster Matrix

Dungeon	Monster Level
Level	1	2	3	4	5	6	Tier
1	1-3	4-5	6	-	-	-	1
2	1-2	3-4	5	6	-	-	2
3	1	2	3-4	5	6	-	3
4-5	-	1	2	3-4	5	6	4
6-7	-	-	1	2	3-4	5-6	5
8-9	-	-	-	1	2-3	4-6	6
10-12	-	-	-	-	1-2	3-6	7
13+	-	-	-	-	-	1-6	8

Now, after you consult this table, you'll refer to one of the individual "Monster Level Tables" (which I'll leave for a later day). But the end of the process is to determine the "Number Appearing", for which OD&D gives some very loose, vague guidance. I've even previously posed this as a question to readers in the past, and gotten excellent feedback: in particular, I was tickled by "if in doubt, as a basis, roll 1d6".

So here's what I do currently:

• If the tier is equal to the monster level, roll 1d6.
• If there is a one-step difference, multiply or divide by 2.
• If there is a two-step difference, multiply or divide by 4.

When multiplying you roll extra dice (i.e., when monsters are weaker than the tier); when dividing you roll one die, divide, and round up on 0.5 or more (minimum one monster; i.e., when monsters are stronger than tier). Note: You'll never have more than a two-step difference between monster level and tier level, based on the modified matrix above.

Here are some examples:

1. We're on level 2 and generate a 1st-level monster. Since that's one step weaker than the dungeon level (tier), I'll roll double monsters: i.e., 2d6 for the number.
2. We're on level 3 and generate a 3rd-level monster. I'll simply roll 1d6 for the number appearing.
3. We're on level 4 and generate a 6th-level monster. Since that's two steps tougher than the dungeon level (tier), I'll roll for one-fourth as many monsters: i.e., roll 1d6 for 6, divide 6/4 = 1.5, and thus 2 monsters appear (note that any die result 1-5 would be only a single monster).

Gygax in both OD&D (Vol-3, p. 11) and AD&D (DMG, p. 175-179) tried to "naturalize" the numbers appearing (e.g., orcs in larger numbers, skeletons in smaller numbers), but personally I don't think that's sustainable. One or the other type will be over- or under-powered (all the time), so it's probably best and simplest to just use a single rule for all monster power levels. The random dice will create some nice variation in any case.

The table and rules above are indicated as Open Game Content under the terms of the Open Game License v1.0a. A copy of the table in spreadsheet form (.XLS) is available here.