Sunday, September 28, 2014

Hit Dice modifiers: More useful than you (or TSR) thought

One of the conventions of D&D that I always found kind of weird and inexplicable is the practice of adding hit points to a creature's Hit Dice (or in very rare cases, subtracting them.)  An ogre, for instance, is listed in B/X as having 4+1 HD.  What exactly is the purpose of giving it one measly hit point more than the roll of the dice?  Meanwhile, the goblin gets 1-1 HD, want it to be a little weaker than the orc?  A few creatures get bigger modifiers, but even so, a bonus of 3 hp is pretty trivial to a troll with 6 HD.

Of course, a creature with a plus to its Hit Dice attacks on the next higher line of the combat matrix - in mathematical terms, it gets a +1 bonus to attack.  And creatures less than one full HD attack on a line below the 1 HD line - in effect, a -1 penalty to its attack rolls.

This is potentially a much more useful and game-changing application of HD adjustments than simply adding or subtracting a hit point or two from a monster's total, and one that the game's designers sadly failed to fully appreciate and develop. 

One thing D&D doesn't do very well is model the classic mismatch between size and coordination.  Fiction and real life are full of examples of big, tough people and creatures that are ponderous and awkward on the attack, and fragile speedsters who strike with uncanny precision but can't endure much of a beating themselves.   Hit Dice modifiers are a good way to stretch the system so that it can model that type of monster, though.  All we need to do is expand the rule a bit, so that instead of a flat +1 jump on the combat matrix for any addition to HD, you give a bonus or penalty equal to the modifier.  A creature with 4+3 HD thus attacks as a 7 HD monster, and one with 2-2 HD attacks as less than 1 HD.  This method gains you a little freedom from the direct correlation between monster size and toughness and its skill in battle, without having to add another statistic to a creature's stat block.

Say you want a massive, ponderous beast that can take a pounding before it keels over, but is slow and ungainly in its attacks. Give it a high base HD, with a hefty minus - say, 8-4 HD.  It still has a good pool of hit points - anywhere between 4 and 60, with an average of 32 - but it attacks with the same probabilities as a much weaker 4 HD monster. 

Or perhaps you want a small, nimble creature that slips past an opponent's defenses with lightning speed.  You could give it 1/2 +3 HD, for a total of 4 to 7 hp.  That's fairly fragile, but the thing attacks with the proficiency of a 3 HD monster (that's a THAC0 of 17 - as good as a 4th level fighter in B/X or BECMI.) You can take it out in one or two hits, but until you do, it's going to carve you up.

In this way, you can design big monsters suitable for low-level parties, and small monsters that can challenge more powerful parties, without having to make them much more fragile or durable than you want.

Sunday, September 21, 2014

The tight spell lists of classic D&D

Magic is an integral - some would say indispensible - part of fantasy stories and fantasy role-playing games.  Sure, you can have a medieval game without magic, but it loses a significant element of the fantastic.  Even games that bar player characters from being spell-casters often do so not to expunge magic from the game entirely, but to keep it beyond the understanding of the players - to keep it wild and fantastic and fearsome.

I like magic in my game.  I like for the players to be able to choose to run spell-casting characters if they want to.  But I also like for magic to be magical - wild and fantastic and fearsome - as much as it can be without making it the province of DM and NPCs only.  That's why I like the tight spell lists of B/X and BECMI D&D - at least as a foundation upon which to build.

There is, it's true, a lot to like about the massive variety of spells in AD&D, as well as various supplements.  They can add a lot of flavor to the campaign milieu, and utility to characters, both PC and NPC.  They can serve this purpose without being added to the standard spell lists.

The tight lists of 12 magic-user spells and 8 cleric spells per spell level are the ones that are most commonly known.  Not every spell caster will know every spell, but most are at least aware of the existence of these spells.  If you don't know Phantasmal Force, you at least know that there is such a spell, and that with a little determination you can probably ferret out a source from which to learn it.  They're the magical meat and potatoes of the campaign.  They allow for a good diversity of functions, and the campaign will survive just fine on a steady diet of them.

Beyond those lists is the whole kitchen sink of spells, every one that's ever caught your eye in another rule set, or an adventure module or supplement, everything that you might devise from your own imagination, whatever you might fancy dropping into your current game world.  Rather than dumping them into the mix wholesale, you carefully pick and choose which ones fit, and where they'll be found. 

There could be any number of explanations why those non-list spells are so rare and obscure.  Perhaps the civilization that invented them fell and the knowledge was lost.  Perhaps they're leftover "beta" versions of common spells that fell out of favor with the discovery of new versions, with surprising bugs and maybe even a few forgotten utilities.  Maybe they were invented by wizards who keep their secrets close to the vest.  Maybe they're banned by the king, the church, or the mages' guild, for reasons ethical, spiritual, or commercial.  (The flimsiest pretense will do - look at the historical reasons in our real world for banning all kinds of things.)  Maybe they can be learned only by dangerous rituals or pilgrimages to sacred or magical sites, or by using ancient devices that project knowledge directly into the caster's mind. Some of them might even have inhuman origins, and can be learned only from dragons or fairies or demons or what-have-you; humans might be able to understand them well enough to memorize and cast them, but not well enough to teach them to another human.

These are the spells that you give judiciously to NPC opponents or allies to make them more menacing or mysterious.  These are the ones you place very rarely in treasure troves to get your spell-casting PCs excited.  These are the ones the players might hear about in rumors, motivating them to undertake expeditions and quests to obtain them.  These are the spells that might convey all sorts of interesting implications about the campaign world and its societies and history.  These are the spice that you add to the dish of meat and potatoes.  They're not essential, but a sprinkling of them adds interest and versatility. 

From a pragmatic perspective, a scheme consisting of a small staple list and a universe of supplemental stuff provides the ease and convenience of the former, while allowing you the freedom to tempt or bedevil your players with more exotic stuff as needed, and as suits the particulars of the campaign and the world in which it takes place.