You have studied a single spell in-depth. Your expertise grants you formidable though narrowly focused arcane mastery.
Prerequisites: Knowledge (arcana) 9 ranks, ability to cast arcane spells.
Benefit: Choose one arcane spell that you can cast to be your thesis spell. When casting that spell, you do so at +2 caster level. When you apply any metamagic feat other than Heighten Spell to that spell, the enhanced spell uses up a spell slot one level lower than normal. For example, an empowered thesis spell uses up a spell slot one level higher than the spell’s actual slot (rather than the normal two levels higher). A spell cannot be reduced to below its original level with the use of this feat.
Example: If you were to prepare an empowered maximized magic missile (assuming magic missile is the spell you choose for your Arcane Thesis), it would be prepared as a 4th level spell (+1 level for empowered, down from +2; and +2 levels for maximized, down from +3).
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new spell.
Source: Player’s Handbook II, page 74. Corrected for errata, including the added example.