2 castings of acid ball
I got 2 castings of acid ball twice with a fighter. I think 10 would be more reasonable, then I could save it and use it for a big fight like the minotaur emperor, whilst not turning me into a full time or even part time caster of it. 2 isn't enough to do anything with. Maybe have a 'minimum_castings' variable if the formula wouldn't accommodate this.