Spellcasting...a point-based system
Spells available for characters to cast
For spell-preparing classes: They choose a number of spells from the entire host of spells they know (entire list + domain spells for clerics or spellbook for wizards, as examples) equal to 1/2 Caster Level times Casting Attribute Modifier. Those are the spells they have "prepared" at one time. This represents pre-measured components, readied foci, and the sheer level of complexity of incantations & ritual procedures they can remember at one time. They may change/swap prepared spells at any time, given an hour of studying/preparing. Spell lists are the same, wizards' spellbooks function the same, characters gain spells in the same way, etc. Include Zero-level spells; they are not exempt or additional.
"Spontaneous" casters, such as sorcerers and bards: They have the same quantity of spells that are known to them, but they need not choose a specific level of spell when they obtain new known spells when advancing levels (i.e. an 8th level Sorcerer gains access to a 4th level spell according to the class table, but in my system, he may choose any new spell up to 4th level. When he goes up to 9th level, he gets any two spells up to 4th level instead of a 4th and a 2nd). The only limitation is that a "spontaneous" caster may not "know" more spells of a higher level than the level previous (i.e. with 3 4th level spells, he may not "know" more than 3 5th level spells). Include Zero-level spells; they are not exempt or additional.
Spells per day...or Spell Points
This applies to all spellcasters. Do not count "zero-level spell-levels." Add the spell levels of your class's "spells per day chart", including bonus spells. Thus, the total for a 3rd level wizard with 15 Intelligence has a total of 7 points. The only thing that I find hard to really teach a player is when a lower level character has an Ability bonus that shows bonus spells of a higher level than they can cast; that character still gains bonus spell points for those, but they act as the highest level of spell they can cast. Thus, our example of a 3rd level wizard would get 11 points with an 18 Intelligence (3 points from spells-per-day table, +1 for bonus 1st level spell, +2 for bonus 2nd level, +2 for bonus would-be 3rd level, and +2 for bonus would-be 4th level).
Casting spells and what they cost
Very simply, a spell costs its level in spell points. Meta-magic level-adjustments add to the cost of spell points (the character must still have the feat to do so) ("spontanteous" casters must still take extra time to cast spells modified by metamagic). Zero-level spells may be cast at will, at no cost in spell points (however, adding metamagic to a zero-level spell will give it a cost to cast). Additionally, if a spell costs (inluding metamagic adjustment) equal to or less than 1% of your maximum total, it may be cast for free (typically up to 1st level spells for high level wizards/clerics, 2nd level spells for 20th level).
Recovering spell points
Characters regain points while they are getting actual sleep or bed-rest. However, they don't automatically get everything back every night. They get 5% of their total back per hour of sleep. Thus 40% per standard 8-hour rest. When travelling in a wagon where they can get a semblance of rest in the rocking wagon (or an equivalent type of broken peace), they get 2% back per hour. All of this does take a minor bit of calculating (takes 10 seconds), but this just takes a calculator or basic skills. Additionally, 3 extra numbers can be recorded near the sheet entry noting spell points (5%/hour of rest, 2%/hour of travel, and 1% of total for free castings). Obviously, people will note that casters cannot use all of their spells everyday. This is intentional; a trade for such great versatility. Plus, how many times in fantasy literature have we heard of wizards exhausting themselves for days after great magical battles?
When a caster is out of spell points: When a caster still needs to cast a spell but has no points left (or not enough), he may dig into himself for power. When he scours himself for spell points, he trades a point of Constitution AND a point of Strength for a number of spell points equal to his Casting Ability Modifier squared (4pts at 14 Intelligence, 9 pts at 16, 16 pts at 18, etc). The traded ability score points are treated as Ability Score damage, and they may ONLY be healed naturally; no form of magical healing will cause them to return faster.
Power Components and XP costs
Nothing costs XP in my game, but anytime an XP cost is called for, a required power component is needed to cast the spell or make the item. Fortunately, my group is such that they work with me and get creative about what sorts of components would be appropriate for a particular spell or item. Some items cost gold to obtain, and some are things they have to quest/trade for. Occasionally, power components are in the form of specific rituals (requiring preparations, time, various numbers of adepts, or even specific conditions like a full moon or magical location).
