Spells as Pseudo Entities
I really dig the idea of spells being almost but not quite sentient/alive. Having an impish personality, itching to escape the mental cages a magic user has erected in his mind.
Each spell exists as a particular "instance". Spells must be captured, summoned or found (in written form). They can't be copied. Although, I leave open the option that they might be bred. Ha! Idea of caster renting out their 5th lvl Fireball out for stud duties cracks me up.
When a caster memorizes a spell from their spell book the spell physically leaves the book and inhabits their mind. It literally disappears from the pages. When the spell is cast (released) or if it escapes (see Mule Abides for possibilities) it scampers back to its "home" in the casters spell book. If the spell book has been destroyed,... who knows what happens to homeless spells. Perhaps they hang about and fuel the Mythic Dungeon or inhabit some discarded bit and transform it into a magic item.
This nicely explains/supports my usual house rule that duplicate spells may not be memorized. Although, in this case modified be if caster actually found additional instances of same spell I would allow them to be memorized. If stored in same book or near one another who knows what could happen? Also, the reason casters generally have to wait til the next day to rememorize spells is that it takes that long (till dawn?) for the spells to make their way back to caster's spell book.
A spell may be transfered (say from scroll found in treasure to caster's spellbook) via memorizing it and then releasing it into a spellbook by performing the scribing ritual. Likewise if a caster loses his spell book, they can, at least, recover the spells they still have memorized by releasing them (via scribing ritual) into a new spell book. With this system I see no reason that spell inscription should be very expensive (scribing is now self-limiting, could still act as gold sink though). Still takes time. It's a mystical/magical process so material more durable than goat skin, such as bronze plates can be inscribed without requiring an engraver.
Hmmm, I guess this nixes magic user scrolls as a commonly producible item, usable to expand number of spells a caster may cast. Not sure that I'm bothered by that. OTOH, various spell storing/stealing magic items and spells gain new significance. Maybe the only way to get the single known instance of some spell is to trick current owner into casting it on you while you hold a spell siphon.
Spells vs Spell Levels vs Slots
Standard D&D magic uses slots. Each magic user level grants 0+ slots of each spell level (a 2nd lvl slot can only hold 2nd lvl spell). The varying levels of slots make "Vancian" sense if you view caster's memory for spells being analogous to electron energy levels (valences) in atoms. I.e, there is a fixed set of spell level slots that are slowly unlocked as caster gains experience.
A common variation (one Eiglophian is exploring) is granting a certain number of spell levels. Any combination of spells totaling this number of spells levels may be memorized. Too much math/juggling numbers during spell selection for me. Also, either too few spells (if total spell levels are kept low) or too powerful even for a "who cares about balance" guy like me (if total spell levels are reasonable).
A less common variation is just granting a number of spells, regardless of level. Besides mechanical fears of being too powerful (I don't think it is really esp if you forbid duplicate memorization and if high lvl spells don't grow on trees) people get it in their head that higher level spells should take up more Vancian memory space. I could take either side of that argument.
A hybrid method I haven't heard mentioned before. Which I'm not sure is a great idea, just throwing it out there for others to consider.
When a caster gains a level and is granted X number of slots, they must at that time choose what level of spell each slot is for. Vancian explanation: they have faithfully performed the daily mental exercises and have finally organized their brain to accept the spell patterns/valence of a particular shape and power.
This puts a lot of options into players hands on how they want to craft their caster. At 5th level maybe they don't know any 3rd level spells and decide it's better to grab another 2nd lvl slot. Conversly maybe after much toil and risk they found 4th lvl spell and want a slot for that. It can be assumed that the regular spell progression from the rulebook is just the most common selection pattern magic users choose.
There are wrinkles and restrictions you could put on it until it meats your personal power/balance threshold.
- No slots > character level. i.e. must be at least 2nd lvl caster to pick 2nd lvl slot.
- Or, Caster lvl > slot level requires. ie. must be at least 3rd lvl to pick 2nd lvl slot.
- Can't skip slot levels. i.e. to get 4th lvl slot must have at least one slot of 1st, 2nd, and 3rd lvls.
- MLM To get slot x of lvl y must have x+1 slots of lvl y-1 i.e must have two 1st lvl slots to get a 2nd lvl slot, must have three 1st and two 2nd to get first 3rd lvl slot.