Greater Spell Focus [General]
Choose a school of magic to which you already have applied the Spell Focus feat.
Benefit
Add +1 to the Difficulty Class for all saving throws against spells from the school of magic you select. This bonus stacks with the bonus from Spell Focus.
Special
You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new school of magic to which you already have applied the Spell Focus feat.