Flexible Wizardry

When you prepare your spells each day, you can choose to keep a number of spell slots equal to %1 [minimum 1] flexibly prepared. Instead of preparing a single spell within each of these slots, you can partially prepare two spells. Anytime after you prepare these flexible slots, you can spend a fullround action to finalize one slot, choosing one of the two spells to be finished and fully prepared in that slot.