- Monsters assessed with 8-sided hit dice as a default. Knowledgeable readers will know that I personally run my games still using the 6-sided hit dice for monsters as they appeared in Original D&D (Vol-2; while using 8-sided dice for fighter hit dice, as per Sup-I Greyhawk). Granted that most people use 8-sided dice, it seemed warranted to run an assessment on that more common configuration. This, then mostly matches the stats as in Moldvay B/X or the AD&D Monster Manual. (Notes: While skeletons & zombies were boosted to 1HD and 2HD respectively, I kept other undead as in OD&D/BX, not the +1 HD boost for other undead as in AD&D. Normal men are therein uniquely 1d6; NPC fighters 1d8.) This will give most monsters a bit more power against the men.
- Fighters assessed with advanced equipment. To measure a raw "equivalent hit dice" value (EHD), the initial assessment program kept fighter equipment constant (chain mail, shield, +1 sword), with the emphasis on correct XP awards. Here, for the purpose of balancing encounters, we may also simulate more expected gear for high-level fighters; plate-mail, shield, sword, and a 20%/level chance of boosting any of those by a +1 bonus (swords still start at +1 by default). Counter to the preceding, this may give the men quite a bit more power against the monsters.
Let's see what happens. First, simply switching from d6 monster hit dice to d8's (men still in chain and shield; no added magic per level):
This makes a fairly small difference in most cases. Previously our toughest monster, the Vampire was measured at EHD 36; now it is EHD 39 (in both cases, equal to 4 12th-level Lords). Hill Giants were EHD 8 and are now EHD 9 (previously worth 5 0-level men and now worth 6). New EHD values are given above if this matches how you run your game; but the differences are not great, and I don't see any need to change XP "boosts" (asterisks) as shown previously.
Now, the case of monsters with 8-sided hit dice against fighters more fully equipped (plate, shield, 20%/level to boost any of their armaments):
Now, that's quite a different story. I've removed the appearance of the EHD column, because these measurements are totally not comparable (and I don't want any readers to be confused by that; again, I suggest using this table for balancing encounters but not XP awards). We see that a fully-equipped Lord of the 12th level can fend off much larger numbers of low-level types: 40 orcs, 45 bandits, 65 kobolds or giant rats, etc. One such Lord has about an equal chances to defeat 2 giants or trolls single-handedly; and 2 or 3 Lords may be victorious over a vampire or purple worm. Note that this is still without any extra attacks by the Fighters (which is more fodder for my frowning against AD&D-style mega-attack counts; surely fending off a half-hundred normal men is sufficient, and we need not further boost that by an order of magnitude!). Also: Fighter stats are on average just straight 3d6; if we dialed that upwards due to expected survival bias, the men would be at even more of an advantage.
Finally, let's include the case as in my games where monsters have 6-sided dice, and men have arms and magic as expected above:
Again, the change in monster hit dice from d6 to d8 or back is not very great. The 12th-level Lord is now only worth 44 orcs instead of 40. Numbers against the upper-level monsters are mostly unchanged. Not a big deal either way.
That said: I would highly encourage any DM's playing with post-Greyhawk 8-sided monster hit dice to try switching back to the original, and rolling d6's for hit dice instead. It's so much easier to find, keep, and use a batch of that die type; as we can see here, the effect in battle is practically negligible; and my players have never noticed the difference.
Want to run these assessments according to your own custom parameters? Here's MonsterMetrics v.1.01 which lets you do that. As usual, download and unzip the first file, and from the command line type java -jar MonsterMetrics.zip to get it running. Now, you can add a command-line switch like -b=3 to indicate the base armor type for your fighters (3=plate, 2=chain, 1=lather, 0=none). Also now included is the switch -p=20 to set the percent chance per level for a magic boost to any item (default is zero if none specified). Finally, changing monsters stats requires editing the monsters data file; included below is the alternate file Monsters-d8.csv with 8-sided hit dice for the monsters (rename this as Monsters.csv to get the program to use it as input). Any interesting new discoveries?