More Monster Metrics, Pt. 3

Last time I posted a table of improved EHD values (link), which takes into account simulated battles between mass groups monsters and fighters across arbitrary levels. Here I'd like to focus on the monsters at the extreme limit of power levels in D&D, where in some places we have clarified our vision, and in others the model may break down a bit or open up other questions.

Single XP Bumps Predominant: The majority of D&D monsters assessed here have either one, or none, exceptional XP awards warranted. That is: almost no monsters are worth more than double their base HD value (the level at which I've indicated a Cook/Moldvay-style "asterisk" for an added XP increment). There are three exceptions: Medusae, Basilisks, and Vampires, which we'll discuss further below.

Big Brutes at Risk to Many Men: Some monsters which in the prior "point estimate" model had exceedingly high values are now seen to be surprisingly vulnerable to moderate-sized groups of normal men. For example: In the first version,the most dangerous creatures were Hydras and Purple Worms; the former was balanced against a single Fighter of up to 44th level (due to its many-headed attacks); and the latter was favored over any single Fighter of arbitrary level (due to its unavoidable Swallowing ability). Looking at the Party-based output, we see that these types are evenly matched by only 10 or 12 Fighters of the 1st level (with chain, shield, and +1 swords). And hence their EHD scores are now 18 and 33 -- not infinite, but rather at the more standard double-HD level.

The reason for this is clear; both these types have abilities in the "high-level killer" category (many attacks, and save-or-die-on-hits), that are not immensely useful against masses of lower-level men (no area attacks). Also, both of these "giant worm" types have pretty low ACs -- 5 and 6, equivalent to chain -- allowing pretty much anyone to reliably hit them. Note: This model doesn't even give the men extra attacks due to monster size. Even limited to the standard 6 melee attacks per round, 1st-level Fighters vs. chain (needing 14+ to hit, that is, 7/20 = 35% to hit) have an expected damage output of 6 × 0.35 × 5.5 = 11.55 points per round. That is, they'll probably be killing about 3 hit dice/heads per round, and even a 10 or 15 HD creature won't last more than 4 or 5 rounds on average.

On the one hand, we might consider this to be a letdown (even our biggest monsters are underdogs to groups of 10 or 20 normal men, say). But on the other hand, this gives us additional motivating material for our campaign world: abominations like these have good reason to remain lurking in the underworld -- they can't afford to appear in the open where organized groups of men can oppose them. Open terrain is strategically advantageous to large numbers of weaker creatures; while maze-y defenses are advantageous to less numerous, but individually more powerful monsters (think: "tank blocks the doorway"). This would be even more pronounced if ranged attacks were modeled, which they are not in this simulator.

Medusae and Basilisks: The Medusa is the only monster shown with two asterisks (HD 4 and EHD 13); and the Basilisk is the only monster with three (HD 6 and EHD 24). Why is that? Simple: They're the only monsters in the list with both low-level and high-level-killer abilities. They both start every combat with a Petrification gaze attack (assumed unavoidable here), and against low-level opponents, a great many of them will fail saving throws and be out of the fight. But if this fails and/or they confront higher-level opponents, then they can still melee with save-or-die effects on every hit, round-after-round (for the Medusa deadly poison; for the Basilisk petrification). This complementary nature of their deadly special abilities makes them two of only three cases where it's really justified to give an XP award for each ability separately.

Note that in the prior one-on-one assessment about a month ago I overlooked the fact that Basilisks in OD&D get petrification for both gaze and touch, which is maintained as the rule throughout the Basic D&D line (Holmes Basic, Cook Expert, Mentzer BX, and Allston Rules Cyclopedia). In the AD&D line, the touch petrification was stripped out, making the basilisk a much weaker opponent due to the removal of that single key word (1E, 2E, 3E, etc.). If I take out the touch ability for the Basilisk and run it through the system here, it gets measured at only EHD 10 -- that is, petrify-by-touch more than doubles its value, as compared to Basilisks with only gaze attacks, according to this model.

Vampire Terrors: So you may have observed that the highest-rated monster in the current evaluation (last in the list) is the Vampire, the only other monster with more than one asterisk -- base HD 8, EHD 36, more than 4 times difference (and so given an unprecedented 4 asterisks here). We've mentioned before that they have an almost comically large number of special abilities -- Flying, Magic-To-Hit, Energy Drain, Regeneration, Charming, Summoning, and Polymorph. If you look into my monster data file, the Vampire special abilities are more than twice as long as any other, literally scrolling off the width of the screen.

Some of these abilities aren't modeled at all in my simulator: like Flying and Polymorph. The Magic-To-Hit is a non-issue, too, because I assume that all Fighters at this level have at least a +1 magic sword (so as to prevent infinite-loop-combats in the simulator, basically). The Charm ability is put in play, but I assume that only works against a single opponent at the start of combat. Regeneration is always potent, of course (and yet something that one might forget about Vampires). Energy Drain of 2 levels is here adjudicated with no saving throw, and also punitively reducing current hit points by the same amount that are lost from max hit points in the level drain. Still, that's been found to not increase risk within a single fight by very much (the same ruling barely gives any benefit to Wights, Wraiths, or Spectres).

The power that really turbo-charges Vampires in this assessment is their Summoning ability -- something that could not be modeled in the prior version that did one-on-one combats only. And here we get into an adjudication debate, because the statistics for their summoned helpers, and how they function in combat, weren't even specified at all within Original D&D. The description for Vampires says simply: "Vampires can command help by calling to them from 10 to 100 rats or bats or from 3 to 18 wolves." Gygax in the AD&D Monster Manual specified that the former was for dungeon settings only, the latter for wilderness encounters. Cook in the D&D Expert rules gave additional options of 5-20 giant rats or 2-8 dire wolves (perhaps to make the fight easier to run?).

The assessment I've done here was run using only the 3-18 wolves option, with statistics taken from the Monster Manual: AC 7, MV 18, HD 2+2, Attacks 1 bite, Damage 1d6 (this is also in line with D&D Swords & Spells p. 18, even though OD&D Vol-2 parenthetically suggested only 1 HD for wolves on p. 20). Note that with an average of about 10 wolves summoned, this obviously accounts for about 2 × 10 = 20 Hit Dice worth of value. Adding this to the prior solo value for Vampires (15) gives 20 + 15 = 35, almost perfectly accounting for the change to EHD 36 seen here. The addition of 10 Wolves adds nearly a Hydra-level of extra attacks against any opponents -- and even better, serve to shield the Vampire from attacks, because of the DMG-style adjudication that melee combatants must roll for targets randomly. (Or on a tabletop with miniatures: the supra-intelligent Vampire should place the Wolves so as to surround, cut off, and block any opponents.)

It gets even worse if we think about what happens if the Vampire summons around 50 or so Rats to his cause in the dungeon. First, what kind of Rats are these? We have at least two pieces of evidence that they are normal, not giant rats; (1) Cook's separate listing for a smaller number of giant rats, and (2) Gygax's inclusion of ordinary rats in the Monster Manual II (in addition, we will see that the end result is frightening enough as-is with just the normal type). In that latter tome, EGG laid out ordinary rat statistics like this: AC 7, MV 15, HD ¼, Attacks 1 bite, Damage 1 point. If anything, I think that the HD listed is too high (1-2 hp, that is, as robust as one third of all normal men; but in our simulator it makes no difference, since all the Fighters do at least 2 points of damage on a hit anyway).

In this case, running the Vampire-With-Rats figure through the existing simulator outputs a result of EHD 47, almost 6 times the base HD value, worth about 5 asterisks of award points. But a few reasons we shouldn't trust this value: First and foremost, it seems less reasonable to say that ordinary rats can block attacks against the controlling Vampire (which occurs by default in the simulator). Certainly as DM I'd rule that a PC can wade through the mass of rats and attack (or shoot) the Vampire if one so wishes. Secondly, the simulator assumes that the entirety of the monster party must be cut down one at a time before the other side achieves victory; and I'd probably say that having come to blows and defeated the controlling Vampire first, the ordinary rats would all scurry away (not stay and fight to their individual deaths). But on the other hand: I would probably give more than the default 6 attacks per opponent to the rats in question; and having a whole bunch of rats swarming all over your whole PC party (magic-users and thieves included), scoring some points of damage every round, is itself pretty distressing. (If I adjust the code in the program so Fighters can direct all their attacks on the Vampire, and controlled animals scatter after his defeat, then Vampire-With-Rats drops back down to EHD 15, and Vampire-With-Wolves goes down to EHD 25; the difference being in the animals' individual damage output before the Vampire goes down.)

Does that level of danger from Medusae, Basilisks, and Vampires seem reasonable to you? Have you remembered to make the most of the Vampire's Summoning ability the last time you used one? (I know I probably didn't.)


  1. I love this analysis! It's very useful to know exactly how tough something is, and worthy of few pencil marks in my Monsters & Treasure book.

    One thing to consider with large numbers of summoned monsters is that they are far more susceptible to Area effects, and as the party may well have a wizard, one Fireball is going to make short work of that rat swarm in a way that a single high level fighter just can't match.

    Also, with something like Medusa, I wouldn't rule that everyone needs to make a save. Even if 100 peasants stumble across her in a wide open space, only the ones at the front are actually going to see her and make eye contact, the rest are going to see their friends petrified and either run or close their eyes. More likely she'll be hiding behind a corner, and then only a few will be petrified. Plus it's a heartless GM that doesn't throw in a few horrified statues to provide fair warning of a save-or-die effect!

    1. Hell, even if you don't have fireballs, Sleep and Burning Hands will work wonders on the rats! Possibly on the wolves as well, depending on whether you give them 1 HD as suggested by Vol-II or the 2+2 or 3 HD given by AD&D - and to be perfectly honest, I think I prefer the 1 HD wolves. Though it's what I grew up with, I now tend to think that AD&D gave most animals altogether too many hit points.

  2. Wonderful post, in a wonderful series on a wonderful blog. I totally love it!

    I think your analysis is spot-on. Regarding the low number of (low-level) fighters needed to take down purple worms et al, this is very much in line with your find that single heroes hardly matter on the battle field, almost regardless their level.

    In the end it is the number of actions that matter in a battle. If an ability can increase your own number of actions (summoning) or decrease the number of the opponent's actions in a drastic way (eg. petrification or area of attack spells), then this is very powerful and is nicely reflected by the table.

    As for your questions, yes I do think the level of danger for the mentioned creatures is reasonable and also how they compare against Dragons and Purple Worms.

    I have to admit that I never had a Vampire in my D&D game (funny now I come to think of it). There might be one in the foreseeable, but not too soon, future, but that depends on the choices of the PCs.

    I have to say that am a bit wary to run Vampires since the White Wolf debacle. Suffice to say that the Vampire campaign didn't go too well.

    1. Thanks! And I agree -- action rounds are the coin of the realm.

  3. Personally, I think the 1/4 HD rats and 2+2 to 3 HD wolves were part of a weird sort of systematic power creep on the part of ordinary animals - similar to the excessive number of attacks given to predatory cats.

    As for vampires, I only used one once. I was playing AD&D, and the Monstrous Manual specified that creatures summoned by a vampire come in 2-12 rounds. One high roll later, the rats were too late and the fight was over before they were slated to arrive.

    1. That's a great point on the delay to the summoning in AD&D. That doesn't appear anywhere in the OD&D or B/X lines that I'm aware of. My rule-of-thumb is that fights usually take around 4 rounds, so the 2-12 mark means that means that about 5 times out of 6, the summoning would be totally irrelevant. That's a colossal difference, of course, under this analysis.

  4. I think this reveals something I've come to love about OD&D: it's not a game of stupidly powerful superheroes, but relatively moderate numbers of normal people can achieve more if they get organised. As you have said, this gives big monsters a reason to hide away and it also means that even high-level PCs can't stroll into town and behave badly without consequences. Certainly some people are scarier than others, but in the end the flatter power curve seems much more believable and makes a more familiar world. That is, if you can accept fire-breathing dragons and magic spells...

    1. Great point! I like it in that direction, too. And why I'm not fond of giving high-level fighters a dozen attacks per round against normal men.

  5. This is an amazing analysis and really useful. Thanks!

  6. 1. Does that level of danger from Medusae, Basilisks, and Vampires seem reasonable to you?

    Yes, based on OD&D rules. It also explains in the campaign world why powerful monsters cannot so easily dominate the entire world. Trained Armies even with low level troops would be able to bring down most monsters given time and position.

    2. Have you remembered to make the most of the Vampire's Summoning ability the last time you used one?

    No, as a player I hated vampire encounters due to level drain. Based on experience awards for vampires it was not worth fighting them.

    1. Good observations. How large of a treasure cache would the vampire need before you were willing to risk it? :-)

  7. I agree that vampire summoning often gets forgotten, but then again magic will counter it better than lots of fighters. In the end though, what makes vampires scary is that they can escape so easily and regroup to attack again. Most DMs will play them smarter than most monsters, or should. Just playing a straightforward fight to the 'death' isn't their strongest suit.