Buffyverse D20

[Essex]

I'm putting the finishing touches on a quick, modern conversion of the DnD/Star Wars D20 system to run a Buffyverse game. So far the basic playtests with my group have gone rather well, but I'm hitting on snag on the magic system, in that the standard DnD magic system just doesn't apply very well, but I'm having trouble sketching out a playbalanced system.

What it needs is this
-a spell point system
At the moment, I'm using the Wound Point/Vitality Point system from Star Wars, and am making the vitality cost equal to the spell level times 10 (this is to keep magic from being abused at low levels). A PC can cast any spell they can learn or find, provided they simply have the vitality to cast it.
-skill check
I'm making the PCs make Spellcraft checks versus 10 + spell level to successfully cast spells.
-ritual casting
At the moment, I'm simply letting ritual casting divide the fatigue cost among the circle/group to make high-level spells available with more effort but without a need for high level characters
-over-casting
a PC warlock/witch can cast spells beyond their ability (ie a 5th level witch can cast True Resurrection if she can just scrape up the vitality cost)
-corruption
if they botch a Spellcraft check they have a choice, the spell is twisted by the Hellmouth into a perversion of the original intention. Also, if they fail or botch while over-casting, the PC must make a Will Save DC25 or be taken over by the magic and risk addiction or slide one alignment down towards Evil.

This is my temporary magic system. I'd appreciate comments or criticisms. I'll also be posting my Slayer and Vampire Templates, as well as Watcher and Demon Hunter prestige classes. A friend of mine is working on a Buffyverse character sheet with the Modern Skill and Feats list. I plan to post a link to it here as soon as he's done.

 

[Essex]

The Slayer Template

The Slayer is a Chosen servant of the Powers That Be. The Slayer is always a young woman, typically 15-17 years of age when Called. She is a champion of Good and charged with the destruction of undead and infernal beings. A Slayer is gifted in superhuman strength, speed, and toughness. A Slayer's highest class is always Soldier or Martial Artist, though she may multi-class freely.

STR +8, DEX +6, CON +6, INT +0, WIS +0, CHA +2

Special Abilities
-Staking - a Slayer automatically starts with the Feat, One Hit Kill, taken with the Wooden Stake and ignores all prerequisites for it.
Wooden Stake Damage 1d4, Threat Range 19-20/x2 critical.
-Weapon Proficiency - proficient in all simple and martial weapons.
-Natural Armor - a Slayer is agile at dodging and more resistant to damage, giving her a +1 Dodge bonus and a +1 Armor Bonus to AC
-Iron Will - Treat the same as the Iron Will feat
-Infernal Bane - any weapon in the hands of a Slayer is treated as an a Bane weapon versus evil outsiders (though the weapon still must overcome the creature's natural damage resistance
-Detect Undead - Slayer may detect Undead at will.
CR +4

Death & Rebirth
A Slayer's power comes from death, according to legend, and she embraces this in her death as well. Nothing aside from a True Resurrection (or modern medical techniques in the right circumstances IE CPR) can bring a Slayer back from the grave. When raised, a Slayer somehow becomes further empowered, receiving an additional +2 to her physical abilities and a +2 to her Will save.