Earlier this month, Paul V. from Dungeon Skull Mountain started a topic on Google Plus asking if there were any Olde Style D&D type games that ditch the standard “Vancian” casting and/or the classic list of spells. Ian B. left a very thorough comment summarizing the approach to magic taken by many different systems that I though might be useful in general, and deserved search engine exposure beyond the Google Plus walled garden. With permission, I reproduce it below (think of this as a Necropraxis guest post). Everything following the separator is Ian’s work.
Mana Point systems have been around for a loooong time (since 1974 at least) and vary in nature, from the simple (each spell costs a number of MP to cast equal to it’s level) to the exponential (each spell costs [level +1]^2 MP to cast) to the incredibly complex (if the moon is in Virago), to the explicit MP cost for each spell. The Arduin Grimoire used a mana point system with casting cost and ongoing cost.
I’ve seen “skill” based systems where the number of spells you get per level is your chance of casting a spell. The dice may be static or increase. One nice system stole from Barony in that if you rolled an 8 on the d8 the magic got out of your control and there was the chance that the Zaire (the greatest wizards of the land) came along, fixed the problem, and removed you from the universe (so that you caused them no more problems).
Speaking of which, Chainmail used roll to cast spells. Which means Five Ancient Kingdoms does as well.
Arrows of Indra doesn’t have spells, instead giving magicians random powers that they can use.
Beyond the Wall has a very nice magic system. Highly recommended.
DCC RPG also has an excellent system for Old School spell casting. Just remember that beginning spellcasters are expected to spellburn in order to get anything done – that’s the limit on casting spells.
Spell Law (the magic system in what was to become Rolemaster) was originally written for D&D, although I’ve forgotten the exact mechanisms (or rather, overwritten them with the Rolemaster descendant). Mana Point and spell list knowledge,
Thieves Guild had some magic stuff in it, although you’d have to dig hard to find it. I think the highly excellent Thieves Guild VI had the most, as well as an excellent set of naval rules and seabourne encounter tables. It was very simulationist though.
And of course the original 1E Chivalry & Sorcery magic system is perfectly extractable and usable in D&D.
Most published variant systems were built for 3E style play. This is mainly because people were trying to recreate the old games they adored in their youth.
I do like Call of Cthlhu d20 which had spells fuelled by the characteristics of the sorceror as the limit for casting magic.
True Sorcery has a complicated system that can be used to determine the DC of spells by assembling effects and limitations . To cast them, simply make the roll on 1d20 + modifiers. Most of the 3E D&D spells are replicated to show you how to do it, but the whole system is a bit too finicky for my tastes. Still it has interesting ideas how to go about thinking of designing new spells.
Blue Rose had a whole different magic system which basically emulated psychic abilities (give or take).
Elements of Magic breaks spells into category effects by level, and was interesting. again, it’s a method of assembling spells. I quite liked it, especially when you start thinking about a spell design system.
GOO’s old Advanced D20 Magic combined a DC system and mana points to try to replicate D&D spells with BESM style abilities. Agian it was to construct a system for constructing spells. Many of the 3E spells translated to this system. Again a bit finicky, but it actually provided lots of ideas for the system I currently use.
I’ll mention PIG’s Atomik Magic and Atomic Grimoire here as well, although it’s not a D20 or D&D system, but contains some interesting ideas on creating a skill and magic point system for it.
And there are many more I can’t remember – all people that had ideas of how to solve the “problem” of D&D magic. Such as Everquest, for example.
And this precis ignores hacks of other systems. I’ve seen both Ars Magica and The Fantasy Trip hacked to fit a D&D game, among others.
If you mean variant magic systems that capture the Old School feel but aren’t applicable to the rest of OSR D&D you’ve got far too many to list. I particularly enjoy the magic of Carcosa.