Improved Flexible Wizardry

You possess an impressive versatility in casting that other wizards lack.

Prerequisite: Flexible Wizardry†, Spell Mastery, wizard level 8th.

Benefit: When you use Flexible Wizardry, you can flexibly prepare a number of spell slots equal to your Intelligence modifier + 4. Furthermore, you can finalize one of these slots with a standard action instead of a full- round action.

Source: Advanced Class Guide