The other option to giving spellcasters MAD is to split up the basics of spellcasting instead of the specifics (i.e. spells).

for instance, what I did was split spellcasting into needing three ability scores: one for magical strength (for save DCs and for determining how high a level spell you can cast), magical flexibility (for determining how many spells yuou know), and magical endurance (for determining how many spells per day you can cast).

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The breakdown went like this:

{table=head]Spellcasting type|Strength|Flexibility|Endurance
Arcane/Prepared|Cha|Int|Con
Arcane/Spontaneous|Cha|Wis|Con
Divine/Prepared|Wis|Int|Cha
Divine/Spontaneous|Wis|Wis|Cha[/table]

The only other thing that I needed to change was the method of learning spells:
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Prepared casters all have a spellbook (divine casters use a "prayerbook" or holy text), or some other limit list to draw their prepared spells from. At each level they automatically get to write down a number of spell levels equal to their class level + their Flexibility modifier. The maximum level of spell they can copy down from buying/trading spells is equal to their flexibility modifier (so a wizard with a +4 Int modifier can't copy any spells of 5th level or higher into their books; they need to learn them by leveling up, or steal/borrow them from another caster's book).

Spontaneous casters gain bonus spells known (same chart as bonus spells per day) from their flexibility modifier.


Lastly, your endurance ability affected the number of active spells you can have at once: 1/2 your class level + your Endurance ability.

Three easy steps, easily explained in the fluff, and casters are SAD, are much less likely to be able to do everything, and can do much less at once.


As for your idea of breaking up the ability scores of the different schools, I'd go about it like this (just my opinion, of course): divide the different schools into whether you think they require power, finesse, or perception/willpower. Power gets Charisma, finesse gets Intelligence, and perception/willpower gets Wisdom.

Personally, I'd split it like this:
Abjuration - Wisdom
Conjuration - Charisma
Divination - Wisdom
Enchantment - Charisma
Evocation - Charisma
Illusion - Intelligence
Necromancy - Wisdom
Transmutation - Intelligence.

This creates a sort of balance between the mental/casting - physical/melee thing, where both sides need to be good in all three of their main ability scores to be good, and having low scores in the other side is still not attractive.

However, you still have the issue of how to do spells per day in such a way that the switch to ability scores remains important, without potentially giving a caster too many spells per day.

I'm not quite sure how to go about that, but I'll think on it.


~Phoenix~