The way I see it, the only way a Blue Mage would work in this game would be to create a Pokémon-like rock-paper-scissors with the creature typing, and have a core set of moves that are all roughly analogous to each other, but change with the type of subtype 'stance' you put on.
Fighting Vilekin? Switch to Cloudkin stance and use Fish Barf.
Fighting Spoken? Switch to Voidsent stance and use Void Fire.
That kind of thing.