## Thursday, June 26, 2014

### Wandering Expectations

A number of weeks ago, poster DHBoggs sent me a nice analysis of setting up dungeons in OD&D, including assessment of likely monsters encountered. I've looked at Wandering Monster Levels and Tables in the past, and he and I came up with basically the same numbers for average hit dice from each of the various wandering tables in OD&D Vol-3.

One thing that he and I agree on (I think I'm more of a latecomer to this observation) is that it doesn't quite make sense to equate "monster level tables" (tables 1-6 on Vol-3 p. 10-11) with "level of the monster" for number appearing purposes (which gets compared to dungeon level on p. 11). If you were to blindly do so, then at the deeper dungeon levels (like 13+), since the "monster level tables" only go up to 6, then you'd be committed to a situation where even the top-level monsters like Dragons, Balrogs, and Purple Worms would need numbers appearing in every encounter multiplied (or exponentiated?) by at least a factor of 7 or more, which becomes totally lunatic if you think about it. It makes much more sense in OD&D, for this purpose, to treat the "level of the monster" as equivalent to its hit dice -- just like it says in the example on experience in Vol-1, p. 18 regarding "a troll (which is a 7th level monster, as it has over 6 hit dice)."

Anyway, one thing this discussion brought to mind is that while we'd both computed the average hit dice (level) of monsters at each of the 6 monster level tables, no one had thought of computing the expected hit dice of monsters at each actual dungeon level. Consider the following tables (or see the open document spreadsheet ODS file here):

As you can see in the final column of numbers, the average random encounter on the 1st level of an OD&D dungeon actually features a monster with 2 Hit Dice. In the 2nd dungeon level, the monsters average 3HD. At 3rd level the average is 5HD, at 4th-5th it's 6HD, etc.

Similar to what we've seen before, the interpretation of these results is in OD&D at the lower levels, the average wandering monster is actually higher level than the dungeon level would indicate. (Later, AD&D tables over-correct and have distinctly weaker monsters, while something like Holmes or Moldvay Basic D&D is about in the middle.)

This explains why in the margin of my copy I subtract -1 from the die-roll for monster level table, such that the monsters more generally match the dungeon level on which they're appearing. At the deepest levels you'll still be doing some multiplications of monster numbers for creatures of around 9 or 10HD, although it's rarely necessary for 12HD Hydras or Dragons, and never done at all for 15HD Purple Worms, for example (which is certainly better than treating all of these types as uniformly "6th level").