Not much outside the general spellcaster feats. Rapid Metamagic at level 9 is a good one, unless you're taking the Metamagic Specialist ACF in place of your familiar. Then, of course, some metamagic feats to go with it.
Another suggestion for the last 5 levels of your build - the adaptation for Nightmare Spinner. The capstone of this 5-level prestige class grants you the ability to overcome immunity to mind-affecting abilities.