SUEL ARCANAMACH! This is an awesome mini-gish PrC. The greatest part of it is that you can't get into it until after level 6 (assuming all full BAB classes), so you could stack on a few levels of Paladin for Cha to saves and Turn Undead (to power Cha based features), or levels of Hexblade for Cha to saves and Dark Companion, or some Battledancer, or whatever.

If you do take the Paladin levels to get Turn Undead, consider being Illumian. NaenHoon rune gets a pseudo Divine Metamagic. Take Persist Spell and for 12 TU attempts, you can make 2 spells persistant on you at all times. I'm currently using Shield and Wraithstrike on mine. Its pretty slick.