The tomes which held Turjan’s sorcery lay on a long table of black steel or were thrust helter-skelter into shelves. These were volumes compiled by many wizards of the past, untidy folios collected by the Sage, leather-bound librams setting forth the syllables of a hundred powerful spells, so cogent that Turjan’s brain could know but four at a time.

Turjan found a musty portfolio, turned the pages to the spell the Sage had shown him, the Call to the Violent Cloud. He stared down at the characters and they burned with an urgent power, pressing off the page as if frantic to leave the dark solitude of the book.

Turjan closed the book, forcing the spell back into oblivion. He robed himself with a short blue cape, tucked a blade into his belt, fitted the amulet holding Laccodel’s Rune to his wrist. Then he sat down and from a journal he chose the spells he would take with him.  What dangers he might meet he could not know, so he selected three spells of general application: The Excellent Prismatic Spray, Phandaal’s Mantle of Stealth, and the Spell of the Slow Hour.

– The Dying Earth, Jack Vance (c) 1950

In RPGs people generally refer to “Vancian” magic to mean the “fire and forget” aspect of spells that Gygax and Arneson copied from The Dying Earth (as well as the notion that one spell = one effect, rather than, say, a range of similarly themed ones).  Each time you want to cast a spell, you have to “memorize” it anew.  It’s a bizarre notion, and one of the first things that subsequent systems tended to toss overboard.  Even if you want to limit the number of times per day somebody can cast a spell, doing it by making you forget how to cast it afterward is regarded as somewhere between strange and stupid.  Even later editions of D&D replaced “memorization” with “preparation.”  What’s often overlooked is that the idea of having to struggle to hold a spell in your mind and having it vanish once its been unleashed is meant to be bizarre, and to make the magic of the Dying Earth seem weird and other-worldly.  These weren’t super-powers, or psionic abilities that other pulp characters might have acquired…spells in the Dying Earth operated by rules that had nothing to do with physics, even science fiction physics.

Another complaint often leveled at “Vancian” D&D magic is that it’s too “prosaic”, or “not magical enough.”  You have your list of familiar special abilities, the number of times a day you can call on them, rules for their exact effects and chance of resisting them, etc.  I actually think that’s largely true, but the problem is not that D&D magic draws on Vance for inspiration, but that it doesn’t draw on Vance enough.  In the process of creating D&D Gygax and Arneson made spells too “war-gamey”…spells in D&D are in a lot of ways just another type of ammo you can equip your troops with, tracked just as if it were arrows, flasks of oil, or Greek fire.  What was lost, in my opinion, was some or all of the real weirdness of the magic of the Dying Earth.  I think that if you wanted some house rules to put the bizarreness back into magic, instead of looking at real world or fairy-tale magic, you could go back to the tales of the Dying Earth and start over from there.

1. First of all, spells are much rarer in the Dying Earth.  Turjan is one of the more powerful and famous sorcerers of the (admittedly decadent and less magically potent) age, and he can master only four spells at once.  In the second chapter, Mazirian the Magician, who managed to capture and hold Turjan prisoner, was capable of five.  So step one is to cut back on the number of spells.  I would suggest limiting a Magic User to 1 + their Int Bonus (however calculated for the edition).  Moreover, though there were once thousands of spells, only 100 are now extant, and a magician such as Mazirian, who has made it his life’s work to aquire them, has about 70 of them.

2. Spells in the Dying Earth are potent.  The Excellent Prismatic Spray was a death sentence: multicolored lines of fire streak in from every direction, transfixing the target and killing it…. Phandaal’s Gyrator spell can lift the target off the ground, holding it and spinning it as the magician wishes, and can be sped up until the victim just flies apart. If you didn’t have a counter to the spells (such as the amulet with Lacondel’s Rune that Turjan possesses), you have no hope of escaping or surviving.  The Call of the Violent Cloud can transport you in moments (albeit uncomfortable moments) all the way across the world, etc.  It may be that there are lesser spells that the magicians of the Dying Earth seldom bother with, but the ones they’re actually shown using are powerful indeed.  So steps two and three are to eliminate the notion of a saving throw against spells (though you probably want to keep it for things like magic from wands or traps), and to get rid of spells castable by level.  If you have a spell and you’re not at your limit, you can force that spell into your mind.

3. It doesn’t seem to be possible in Vance to use two “slots” on the same spell.  If the Excellent Prismatic Spray is the only offensive spell you have access to, you’ll have to round out the spells you memorize for your adventure with others that might be useful.

4. Memorized spells still take time to cast, enough time that, for instance, a character verbally threatened by somebody who knows the Excellent Prismatic Spray can successfully counter-threaten to push a handy button and drop the caster in a pit faster than the spell could be completed.  Pretty much all editions of D&D can handle this, as long as you assume that casting spells isn’t instant.

5. It is possible to screw up casting the spell, with bad results.  If you accidentally transpose a pair of “pervulsions”, the effect of the spell can be reversed, or go off on you instead of your intended target.  Professional magicians such as Turjan, Mazirian, and Ioucounu don’t seem to worry about this much, but it happened to Cugel the Clever twice in succession. If you want to retain the idea of spell levels, you could require a roll for attempting to cast a spell greater than your current level, with penalties for just how far beyond your current abilities it is.  The roll is made when you actually attempt to cast the spell, not when it’s first memorized.  Or you could only apply a rule for checking for spell failure if a non-magician attempts a magic spell, similar to the classic D&D rules for thieves attempting to use magic scrolls.

6. Spells are something that can only be acquired through adventure, or from a mentor.  There are no generally accessible libraries, or magic shops that will sell you a book or scroll of them, and while magicians can share their spells with their colleagues, they guard them jealously from their rivals.

7. Spells are strange.  The Call to the Violent Cloud doesn’t just whisk the caster to his destination, it summons a strange and malevolent (or at least indifferent) being to accomplish the task, that must be addressed carefully according to ritual:

All was quiet; then came a whisper of movement swelling to the roar of great winds. A wisp of white appeared and waxed to a pillar of boiling black smoke.  A voice deep and harsh issued from the turbulence.
“At your disturbing power is this instrument come: whence will you go?”
“Four directions, then One,” said Turjan, “Alive must I be brought to Embelyon.”
The cloud whirled down; far up and away he was snatched, flung head over heels into incalculable distance.  Four directions was he thrust, then one, and at last a great blow hurled him from the cloud, sprawled him into Embelyon.

(Note, by the way, that Embelyon is either another planet, or perhaps another dimension entirely, not just a far-off place on the Earth.)

8. Because magic is so limited in applicability, albeit powerful when applied, Vancian magic users are capable of fighting with a sword or by wrestling if they have to.  They’re no Conans, but they get by.  I’d keep the hit point and armor restrictions, but lift the ban on using swords and other one-handed weapons.

9. It’s never explicitly spelled out, but it seems that there is no particular limit on memorizing a new spell once one has been cast…neither casting the spells nor memorizing them is particularly taxing.  In their lairs, where they have all their spell books and time to memorize and cast at their leisure, magicians seem limited only by the relatively small (minutes perhaps?) amount of time it takes to memorize a spell.  It does seem that is it extremely difficult to create copies of existing spells.  While the magicians do eventually acquire them, and even teach them to each other if on friendly terms, it seems to be an unthinkable risk to carry an extra copy about in case of need.  They select the spells they venture forth with carefully, and husband them wisely if they can, but they never ever are seen to have a spare or even to have contemplated the possibility.

You can find spell name generators for Dying Earth-style spells here and here, as well as some additional discussion of Vancian magic, but while the name of the spell is an important part of its flavor, the thing you really want to concentrate on is that the effects be potent and memorable. With all due respect to one of my favorite bloggers, Dr Rotwang of I Waste the Buddha With My Crossbow, simply attaching Vancian names to existing D&D spells isn’t good enough. D&D spells are constructed with a war-gamer’s notion of balance, both against the abilities of other classes and the toughness of opponents. A Vancian version of Sleep, for instance, ought to at least cause the target to sleep forever, preserved and unchanging, until countered (much as the Spell of the Forlorn Encystment sinks the target deep within the Earth to remain alive and trapped, but unaging and undying, until the spell is broken, bringing them alive and blinking, with their clothes rotted to dust, to the surface once more). The spells in the Dying Earth are limited by whether there is a spell applicable to the situation (and whether you’ve memorized it), but where they do apply their effects tend to be absolute. Knocking out 2d8 hit dice of creatures until they waken naturally or are awakened by force is just weaksauce.

So, if you make all those changes to D&D magic, will Magic Users still be a playable class?  I think so.  At low levels, a spell like Sleep is an encounter-ender against a lot of foes anyway, just as at mid-levels Fireball can be.  What tends to happen in D&D is the number of truly potent spells (relative to the scope of the adventure) that a wizard can use during a single day remains fairly constant, while the scale of enemies ramps up…  what a truly Vancian system would tend to do is just get rid of all the minor spells that the wizard ends up with (often more than he’ll ever cast in a single day), and eliminate the process of “trading up” from Magic Missile to Fireball to Meteor Swarm (or whatever).  The problem, if there is one, would be that a beginning mage armed with the Excellent Prismatic Spray or something similar would be a threat against an ogre, or perhaps a dragon or other big nasty, possibly even including a much higher level character.  To the extent that this is a genuine problem, and not just blind allegiance to the leveling treadmill concept in D&D where everything scales up in power as the PCs do, you could certainly solve it by restricting the spells available to the PC magic users until they reached a level where you thought a single-target instant-kill spell was appropriate, or by giving special opponents abilities and items such as Laccondel’s Rune to counter it.  Personally, if I were to try this, I would try very hard to just live with it, and design my adventures so as not to assume that 1st level characters are ants compared to high level characters and monsters, and that under the right circumstances even the powerful can be threatened by the lowly.

What about Vancian magic in non-D&D systems?  I think most of the same principles apply, though the mechanics might differ slightly.  In Savage Worlds, getting a new spell “slot” might be an edge, with the limit that you can’t take the Edge more than once per Rank, while individual spells would be acquired by adventuring.  The Arcane Background would probably grant 1 slot and the knowledge of 3 initial spells and casting the spells wouldn’t require Power Points or a casting roll.  In some ways, adding this kind of magic is easy in almost any system (except perhaps ones like HERO, that expect exact cost-accounting for every aspect of every power), since the rules on how many times you can cast a spell are perfectly clear and the effects of each and every spell are sui generis.  As long as the GM is prepared to deal with the consequences of allowing a certain power in the game, there’s really no limit or constraints on what a spell might do.