This is a really cool battle system! I like how my party is kinda doing their own thing and I'm just in a supportive role, where in most games you would be selecting every little thing each member does. Makes them feel more alive. I'm a big fan of the Axe Boot.
Unfortunately I really suck at these kinds of games so I was very quickly overwhelmed after the tutorial.
My only suggestion would be to allow switching the selected spell with the number keys rather than only the scroll wheel. And maybe showing the name of the spell as a reminder to what it does.
Good luck on whatever game you're using this for!
(also im obligated to complain that there's no linux build and I had to run it through wine)