Ah, a lot of characters have good spells.
Yes, Clea's is pretty good.
Tamara with her Ominous Thoughts is awesome too, but you get her quite late in the game.
Zetta's Battle Dance is constantly improving and a huge plus.
Zara's Tornado Strike Lv4 can wipe out an entire enemy party.
Yu's Divine Irradiation is very effective on some enemies too.
I can't even remember all the spells I've used!