Something else you should know about #onebattlespell.
If you assign a #onebattlespell to a commander and he has the paths to cast the spell naturally, he can cast the spell throughout the battle even if the spell has not been researched.
For instance, if you gave an air 3 commander #onebattlespell for Thunderstrike. He could cast Thunderstrike throughout the battle from month one on, even though the nation had not researched evocation yet.
I am using #onebattlespell heavily in my Master of Magic mod to differentiate the Wizards and the heroes and so far it has made them unique and cool
.