[calmon]

Suggestion

You've another option in the 'Magic' menu: a battlespell list.

Here you can find every battlespell (maybe only the researched one).
Now you can make spells blacklisted which means none of your mages autocast it.
You also can whitelist spell which means mages autocast this one with a high priority.

Optional: You can set a spell as not boostable wich means none of your mages uses additional gems to cast it.

This list applies for all mages in a nation so the micromanagement is very limited.