Almost every class could use something to make it better.
Myth- Need a damaging spell that doesn't double hit. If they lowered the power of ninja pigs it would put Wizard 101's icon back in because the ninja pigs are iconic.
Life- They need something that hits everything. Maybe something like tree root that puts something that looks like the centaur tree on every enemy. It would make life be viable as a damaging option.
Death- They could use something that everything else except life and balance have. The spell that is like a permanent trap. It could be named Funeral Service and increase the power of all death spells by 25%.
Balance- They might need something later in the game that actually is Balance.
Fire- Possibly a trap that increases the power of damage over time spells.
Ice- They specialize in high health so why wouldn't they have just one healing spell?
Storm- I think they could use something that does regular damage to all enemies. I mean, other than Tempest and Storm Lord don't you think they should have a regular damage to all enemies spell?
P.S. These spells should probably be implemented on completion of Mooshoo or at level 35.