These are from a new homebrew campaign world I am designing... the magic system is using a modified spell point system.
Subschool Focus
[General]
Your spells in a specific subschool of magic are much more potent.
Prerequisites: Spell Focus in specific school
Choose one subschool of the school you already have spell focus in. Any spells with that subschool have an additional +1 added to the Save DC for that spell. This stacks with the bonus from Spell Focus. For example, a caster with Spell Focus: Invocation and Subschool Focus: Fire would cast fireballs with a +2 to the Save DC.
Greater Subschool Focus
[General]
Your subschool spells are even more potent.
Prerequisites: Spell Focus in specific school, Subschool Focus in specific subschool, Greater Spell Focus in same specific school.
Choose one subschool for which you already have a Subschool Focus in. Any spells of this subschool are now cast with an additional +1 to the Save DC for that spell. This gives a total of +4 to the Save DC for all spells within that subschool (+2 for the two Spell Focuses, +2 for the two Subschool Focuses).
Mana Battery
[General]
You are capable of producing more innate spell points.
Prerequisites: Caster Level +1 or higher
The bonus spell points given for your chosen primary attribute are doubled.
Craft Spellgem
[Item Creation]
You may create a one-shot spell storage item, much like a potion or a scroll, but useable by anyone and storing any level spell.
Prerequisites: Craft Arcane gem, Craft Storage Crystal (These two feats have not been fleshed out yet)
Using a Drained Crystal, a the spell-caster may store within it a single spell of any level, provided he meets the casting requirements and has a drained crystal of sufficient power. Spells may be stored according to the following chart:
Spell Level (Cost to Enchant)
0-2 (Caster level x spell level x 100 GP, 1/25 price in XP)
3-5 (Caster level x spell level x 150 GP, 1/25 price in XP)
6-7 (Caster level x spell level x 250 GP, 1/25 price in XP)
8-9 (Caster level x spell level x 500 GP, 1/25 price in XP)