I had an idea for an alternative spellcasting system that combines a few of the existing alternative systems as well as a few new things. This is designed for use in a magic heavy campaign, but I'd like to get it balanced so that it doesn't make spellcaster's absurdly more overpowered than they already can be.
Caster Level
Caster Level will be determined through the Magic Potential system outlined in I think it was either Complete Mage or Unearthed Arcana... It's the system where all classes increase Caster Level in a method similar to Base Attack. Full CL spellcasters gain 1CL per level, Half CL spellcasters gain 1/2CL per level, and all non-casters gain 1/4 CL per level. There is no division of CL from one spellcasting class to another, though feats and class features that stack CLs still apply as normal. So a Wizard:5/Cleric:2 would have a CL of 7 rather than 2 separate CLs of 5 & 2.
Prepared/Spontaneous Spellcasting
All spellcasters are treated as Spontaneous spellcasters and need not prepare their spells each day. Instead, classes listed as Spontaneous spellcasters gain Spell Points per day rather than Spell Slots per day using the Spell Points progression charts found in Unearthed Arcana. Additionally, all spellcasters use Bonus Spell Points rather than Bonus Spell Slots. This system gives Spontaneous Spellcasters added versatility to their spells by using Spell Points for all of their spellcasting. Whereas Prepared spellcasters have a set number of spells of each level they can cast each day in the form of Spell Slots and a small pool of spell points to give them a little versatility.
Metamagics
Metamagic's function as normal for any Spontaneous spellcaster. Prepared spellcasters may use their spell slots to prepare a Metamagic feat ahead of time without specifying the spell, so long as they have a slot equal to the level increase of the Metamagic(s). Prepared spellcasters may also add metamagics as a spontaneous caster using any combination of Spell Points and/or a Spell Slot, use of a combination requires that the spell slot in use must either equal the level of the unmodified spell or the level modification for the metamagic. Use of spellslots to prepare metamagic ahead of time allows a prepared spellcaster to apply any single spell slot worth of prepared metamagic without increasing the casting time of the spell, adding additional prepared metamagics however will increase the casting time as if added as a spontaneous caster. More than one prepared metamagic may occupy the same spell slot so long as the total level modification is equal to the level of the spell slot.
Multi-class Spellcasting
Spell Points and Spell Slots are shared across all spell casting classes. As such a Wizard/Cleric may cast spells using their spell slots and spell points granted from either class. However, they may only use Spell Slots up to the level permitted by your class levels, likewise for Spell Points. So a Wizard:6/Cleric:2 could use up to 3rd Level Spell Slots on Wizard spells but may only use 1st level slots on Cleric spells.
Domain Spells
Domain Spells remain unchanged in this system.
Arcane Spell Failure
Arcane Spell Failure remains unchanged in this system.
Comments? Suggestions? Concerns? Changes? Fixes? Balances?