Wednesday, March 22, 2017

Dungeon Random Monster Level Determination

In OD&D and AD&D, wandering monsters could appear on both lower and higher levels of the dungeon than their “normal” level. So you could roll an ogre on the First Dungeon Level, or kobolds on the Sixteenth Dungeon Level.

Appendix C of the 1e Dungeon Master’s Guide has a detailed matrix to determine which “Monster Level” to use for each encounter. The DMG’s use of the term monster level is roughly equivalent to the 3e term “Encounter Level.” The various Monster Level tables in Appendix C (labeled I through X) group encounters, rather than monsters, of roughly similar difficulty, so the “Monster Level III” table has 1d6+1 bugbears, 1 ochre jelly, or 1d3 ogres.

Appendix C’s Dungeon Random Monster Level Determination table allows for a fairly wide spread of results, though most will fall within plus or minus three levels. This range is workable with 3e, but because of the steeper power curve it would be harder to go beyond that. You just couldn‘t add enough kobolds to ever make a real EL 16 encounter.

Random Encounter Level Matrix (d20)
Encounter Level

AD&D adds an interesting twist: if your monster result is from a higher or lower table than the dungeon level, the DM is expected to adjust the number appearing to make a balanced encounter appropriate for the dungeon level. Under “Monster Encounter Adjustment for Relative Dungeon Level”:

Lesser monsters on lower levels have their numbers augmented by a like number of the same sort of creatures for each level of the dungeon beneath that of the assigned level of the monster type encountered. . . . Greater monsters on higher levels will have their numbers reduced by 1 for each level of the dungeon above their assigned level, subject to a minimum number of 1.

So the Monster Level III encounter table lists 1d3 ogres. If encountered of the Second Level of the dungeon, they appear as 1d2 ogres. If on the First, only a single ogre. Going the other way, on the Fourth Level you would encounter 2d3 ogres, and 4d3 on the Fifth. And so on. The math for 3e encounter levels is somewhat similar. Halving the number encountered results in an EL of -2; doubling the number encountered results in an EL of +2. The following table adjusts number encountered based on relative EL:

Numbers Encountered Adjustment for EL
Three ELs LowerTwo ELs LowerOne EL LowerOriginal Numbers AppearingOne EL HigherTwo ELs HigherThree ELs Higher

DMG‘s Appendix C clearly makes an effort to create encounter results that are of appropriate difficulty. Sometimes more recent editions of D&D get knocked for only providing “balanced” encounters to entitled PCs, but the truth is Challenge Rating or Encounter Level are not all that different from the guidelines in Appendix C.

The old Monsters & Treasures Assortment supplement (1977–1980) had an interesting bit of advice:

The assortments . . . have been randomly selected, but they are carefully balanced nonetheless. While it is possible to use high level monsters on the first level of a dungeon about to be entered by experienced players, it would be certain death to use even second level monsters against a party of first level players. In a similar vein, it is not good practice to assign higher level treasures to lower level monsters, as this will allow players to gain experience too rapidly.

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