Let's see I'd want decent arcane casting, plus good stats like BAB, AC, HP and damage might be nice. Plus ways to get out of grappling, paralysis, disease, petrification, etc.... Skill-monkeying might be nice but there are plenty of ways around that in most campaigns. Defense is hard without any armor, and most of the fix-its are divine yet low level. I'd have to go dex and range with a way to use divine scrolls.

So... arcane caster / archer / something with UMD. So... sorcerer / fighter / rogue . Sorc for charisma synergy. Though any similar combo could do. Maybe x/x/bard but as long as I can greater invis myself and have full BAB I might as well grab sneak attack damage.