Spell Specialization

Select one spell. You cast that spell with greater than normal power.

Prerequisite: Int 13, Spell Focus.

Benefit: Select one spell of a school for which you have taken the Spell Focus feat. Treat your caster level as being two higher for all level-variable effects of the spell. Every time you gain an even level in the spellcasting class you chose your spell from, you can choose a new spell to replace the spell selected with this feat, and that spell becomes your specialized spell.

Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a different spell.

Source: Ultimate Magic