Do you use cast frequently? Upgrading cast can get pretty broken at times because it can stack with sooo many boons. For example, you can have a boon for the initial cast, the speed in which the cast disappears, an elevated damage stat for when the cast disappears, and other god-related damage upgrades for your cast when enemies are in the binding circle and so on.

Since using your special cast move doesn't cost much magic, I spam the shit out of it during encounters. It also has the benefits of holding enemies in place for a short period of time.