First, I think key ability being Cha will be nice because of Unearthly Grace: Sorcerer/Elemental Savant of Water/Archmage
Then I found psion seemed can beat Mastery of Elements: Sorcerer/Wilder/Cerebremancer
But this knows too few powers. Since the DC of Energy Ball can be high (+1 per 2 points added), psion my do a job: Sorcerer/Psion/Cerebremancer
Suddenly I realized other ways. More & more ways come into my head: Wilder/Wizard/Cerebremancer, Wilder/Druid/Psychic Theurge (but I don't like druid...), ... each has advantages & disadvantages, and I'm confused now
So any advices?