Ok, so after you master your school spells. Like i learn earthquake for myth, cyrus sends me to a new world which should be added after a new lvl cap. Then we get a new set of spells pretaining to our school. So it is probably gonna be more like defensive spells like you can train tc like life bat and etc.
If this doesnt look good, then we could make something like, you a get a new set of trainable spells. Like you get 5 more spells that are all available to you, just trainable polymorphs that turn you into something into your element Myth Troll Polymorp Cyclops Humungaphrog Minitar