What are you writting your Arcane Thesis on? The most obvious answer, IMO, would be Enervation, although I notice a distinct lack of the Split Ray feat. Split Ray Empowered Enervations are stupid good, especially if you roll well. At the price of a 6th level spell, thats awesome. Burn an 8th level slot on Quickened Split Ray Enervation, or a 9th level on Quickened Split Ray Empowered Enervation for a 1-2 punch that packs 8-12 negative levels. Giving someone that much of a penalty to hit, not to mention 40-60 hps lost and the severe drain of high level spell slots is game ending for just about anyone.

Also, I'd move Master of Shaping down, and not even bother with Master of Counterspells. Take Spell Like twice if you have to. Once for Time Stop and once for...Teleport? Otto's? Greater Shadow Evocation?