Glass Cannons and Meat Walls

(Some half-formed thoughts on variable monster HD)

Normally I'm a devoted adherent of the hp as combat fatigue school of thunk. Coming from a WFRP background the idea that you only need to land one mortal blow just seems intuitive to me. But what about the worldview that deems hp to be a measure of tissue damage? I was thinking about this in the light of some recent musings on the old Monster Manual II ("All storks, all the time"), flavoured with some idle speculation about Tao of D&D Alexius' ideas on why whales are unkillable unless already beached (that whole pre-modern whaling industry; never happened), and on Jo Bloch's currently-in-development labour of love Gygaxian AD&D 3E speculato-clone Emprise (huh, I thought we already had Hackmaster? :) ).

I'll come to my main point via a digression if I may.

[tangent]
In the beginning was OD&D, and OD&D gave us the unified damage mechanic. Weapons all did d6 damage, all hit dice were d6. And, for a time, it was good.

Then came Greyhawk, and in its train came variable weapon damage, d8 hit dice, and x+y notations for HD (you know, roll so many HD, and add a flat number to the total. Enhances survivability, and bumps the beastie up a row on the hit matrix). All good stuff, for a given value of good. x+y HD notations are fine and logical for something like a bugbear (3+1HD), and, sure, what's wrong with a Balor having 8+8 HD? That's +1hp/HD on what should be a proverbially hardy monster; where's the harm in it? A Con of 13 gets you the same...

And again, for a time, it was good.

However, by the time AD&D was in its pomp, use of the x+y HD notation was getting a bit OTT (as things are oft wont to do when excess is not curbed by punkish iconoclasm). By the time the FF & MM2 were published something downright odd was going on. Hit Dice had become divorced from both monster power (special attacks, SLAs, monsters as casters, etc.), and from durability in a 'knock down, drag out' fight. Hp boosts were being used as a 'virtual HD' mechanic, giving a bonus to survivability against hp damage that didn't boost attack matrix placement and saves out of whack. Fine, except that sometimes these bonus hp almost outweighed the hp derived from HD.

Presented for your consideration, a few choice examples of the phenomenon:

+1 hp/HD
Hollyphant 9+9
Yagnodaemon 13+13
Shedu, Greater 14+14
Verme: 18+18
Shadow Dragon N+n (on top of their screwy dragon hp figuring rules)
Elemental Grues (all bar one) N+n
Heirarch Modrons (all) N+n
Foo Creatures N+n
Pedipalps, Scorpions, Solifugids (all) N+n

+2 hp/HD
Swan 1+2
Elfin Cat 3+6
Taer 3+6
Saltwater Troll 6+12
Moon Dog 8+16
Derghodaemon 11+22
Ultrodaemon 14+28

+3 hp/HD
Nycadaemon 12+36
Arcanadaemon 13+39

+4 hp/HD
Tri-Frond Flower 2+8
Ju-Ju Zombie 3+12
Deva (all) N+4n
Hydrodaemon 9+36
Mezzodaemon: 10+40 HD

No longer could you glance at a single number and see that this beastie would have - at least on average - so many more hit points than that one, or that these two nHD monsters might both be equivalently dangerous to the party. The clear correlation between hit points and damage (one sword hit = one hit die) had been entirely lost. A fundamental part of the primary purpose of the HD system, and a useful DM tool, discarded thanks to system bloat.

And it got odder. Some monsters appeared to have had pointless additional hp doled out to them for no good reason at all. I'm trying to imagine exactly what had made the writers so adverse to having to write a single lonely number in the HD row of the monster entry. There was just no perceptible rhyme or reason to it.

• I mean, would it really have destroyed the conceptual integrity of the Behemoth (a big mundane hippo) to change it's HD notation from 10+5 to 11? Or the Polar bear from 8+8 to 9HD?
• Likewise with the Firbolg and Fomorian giants. What earthly use is an extra +1-3hp to a 13 HD melee monster? A simple +1, yes. That bumps a monster up the hit die matrix. But +1-3?
• Similarly, if someone can explain to me how a Drelb is at all enhanced in any meaningful way by having 5+3HD, rather than 5+1, I will put one thing of their choice into my mouth.
• The bizarro rolls on with a Giant Firefly by having 1+4 HD. ("Pourquoi?" "Parce que! Silence!")
• Ditto the Twilight Bloom with its lolrandom, but oh so Barrier Peaksy 3+8HD.
• As for the Giant Dragonfly: 8+1-8HD. The logic entirely escapes me. To any non-Martian that should just be 9HD.
• When a typo omits the '+' you get the nigh-unkillable 43 HD pyrochicken (hat-tip: Jeff Rients).
• And the Alu-demon write-up. Well that's just a mess: 6+2 to 6+6 (4-24 for Con bonus, if applicable). "Hurh? Rhot the ruk Shaggy?"

All this fiddly madness, seemingly just to preserve the sacred cow that monster hit dice must only ever be d8s. An orthodoxy that has a notable exception within the very book that offers up most of this strangeness: the Yochlol, d10 hit dice.

"FFFFUUUUUUUUUUUUUUUUUU-!!!"

(deep breath)
[/tangent]

That refreshing little rant about the deficiences of an excessively baroque system aside, we come to the actual substance of this post. Variable monster HD in Labyrinth Lord, and why the very idea is not a catastrophic blasphemy that'll bring it all crashing down around us.

There's Gygaxian precedent for it, so this is hardly filthy 3E-infected innovation for the sake of it. According to our esteemed Greyhawk Grognard EGG's own wishlist for a Gygaxian 3E included variable monster hit dice. I imagine these would have worked in a not-dissimilar fashion to the ones eventually b0rked into existence for WOTC's 3E: base HD by type, plus additional hp per HD based on creature type, physiology and whatnot.

The relevant quote is:

I say that as barbarians get d12 for HPs, then clearly extrapolation of the same principle must apply to large and vigorous creatures. This mitigates the potential increase in PC prowess. As a matter of fact, adult critters were assigned 7-12 HPs per HD in my AD&D campaign--have been given the same in what I have designed for the C&C game system. Also, with increase in damage due to Strength, all large and powerful monsters, including ogres and giants, gain a damage bonus equal to their number of HD.

Admittedly, this is not in the UA work, but it logically follows, and would have been included in the revised edition of AD&D that I was planning.

“Actually I planned to go through the monsters' roster and re-assign HD types--d4, d6, d8, d10, and d12. While doing that in regards to the HPs of each type, the monsters' chance to hit based on number of HD would not be affected.

As too often "weak" monsters were randomly generated, I also planned to have robust adults possess HP totals of something over 50% of the possible maximum by using a HP generation system such as 3-4, 4-6, 6-10, 7-12 using the appropriate die to determine the actual number generated--d2, d3, d5, d6. Non-robust--immature, old, sick, injured, or even non-physically active sorts such as spell caster--monsters would have the obverse HP range using the same type of die without addition.

(source: AD&D's Lost Second Edition)

Hmmm. You know, that makes a little more sense of the HD oddities in the MM2. If only Uncle Gary had taken the time to explain the shift in his reasoning. A simple footnote in the introductory section of the book would have done. Oh well...

Some purists might rage and fulminate against any hit die that isn't a d8 (or a d6 if you're an OD&D arch-purist), but ~if~ hp are read as tissue damage I can't see why variable hit dice types (sans the full-on "and us too" madness of "HD: N+eleventy-three-and-a-half") mightn't work. A large, burly monster should be able to shrug off more bashy-bashy damage than a small one, that's just intuitive. Problem is, just adding more HD in D&D also boosts "not directly related to withstanding pummelling" stuff like hit probability and saves. So, between the AC system and fixed HD, there can be no big-but-clumsy meat wall monsters, no fragile-but-slippery glass cannons.

Here's my modest proposal.

1. Base HD are determined by monster size.

Easily done. There are notes on how big beasties are in their descriptions, and AD&D 2E had a handy little monster size chart that divided creatures up by degree of HUEG.

Size	HD	Example
T (less than 1')	1hp/HD	Poxie, housecat
S (1'-4')	d4 (av 2.5)	Kobold, giant shrew
M (4'-7')	d6 (av 3.5)	Human, black bear
L (7'-12')	d8 (av 4.5)	Ogre, horse, cave bear
H (12'-25')	d10 (av 5.5)	Elephant, giant
G (25'+)	d12 (av 6.5)	Dinosaur, whale, purple worm, roc

2. Base HD are modified by the type of monster, or by character class.

Swarm/yard trash monster	= -1 shift
Spindleshanked Fairy Race	= -1 shift
Barbaric or predator race	= +1 shift
Harder than meat (made of wood/stone/iron)	= +1 shift
Demon/Dragon*	= +1 shift
.
Arcane Caster (W, E)	= -1 shift
Warrior Class (Dw, E, F, 1/2)	= +1 shift

* Dragons get an additional fillip to their HD type because, well come on, they're still the iconic antagonists of the setting. Even a dinky little St. George ganks a half-grown crocodile dragon should be as tough as old boots and require substantial tenderising. Ditto demons. Unnatural vitality, rock star villain status, and all that...

Worked examples

• Giant leeches (small-sized yard trash) have 6d4 HD, rather than the 6d8 that currently makes them as tough as a rhino, a tiger, an orca, or a 20' long crocodile. (No, really. IANMTU.)
  
• Halflings (small-sized, but a warrior race) have d6 (d4 > d6), as do imps (small + demon).
• A normal human will have d6 HD. Fighters and hardy warrior race humanoids will have d8 (albeit for different reasons).
• A large animal, like a horse or cow, will have d8 HD. A large predator like a polar bear, or warmongering and flesh-guzzling big humanoids like Ogres and Trolls, will have d10 HD.
• Huge animals, like elephants or brontotheriums, will have d10 HD. Huge "I smell the blood of an Englishman!" brutes, like giants and treants, get d12 HD (d10 for size + being hardcore/carnivore bonus).
• Gigantic "Leg it lads!" stuff - dholes, purple worms, T-Rexes and the like - will have d12 HD across the board.

This should take little or no extra time, either in prep or at the table. Simply roll/decide hp for the type of monster as you would normally, only with different dice. You're a DM, you have dice in abundance, right?

Some example monsters

Monster (Size)	LL HD (av hp)	Mod HD (av hp)
Purple Worm (G)	15d8 (av 67hp)	15d12 (+2/HD = av 97hp)
Triceratops (G)	11d8 (av 49hp)	11d12 (+2/HD = av 71hp)
Elephant (H)	9d8 (av 40hp)	9d10 (+1/HD = av 49hp)
Cave Bear (H)	7d8 (av 31hp)	7d10 (+1/HD = av 38hp)
Fighting Dog (S)	2+2 (av 11hp)	2d6+2 (-1/HD = av 9hp)

This variant would allow all the PC classes, and most of the iconic monsters, to retain their normal HD, but it also gives you proper meatwall monsters (rocs, dinosaurs, whales, etc.) which don't have insane combat skills or beefcake saves. It also offers the option of including spindly-boned glass cannons - like middling HD faerie creatures - which (IMO) ought to have decent saves and hit chances to go with their sneaky tricks, but should squish good and proper when you finally manage to lay a glove on them.

I know, I know. This is the antithesis of the elegant simplicity of OD&D/EPT, where both hit and damage dice were *always* d6 and the world makes clear sense. But when you've already got variable damage by weapon size (as in LL), why not go the whole (demon)hog and have variable monster HD?

Thoughts? Objections? Reasons I should have my fingers broken for tinkering with the exquisite balance of the B/X-LL mechanics?