Posted this else where under spell book discusion, hadn't noticed this thread yet so reposting here:
As an idea for tournament play, something similar to another idea for Thunderstone some friends and I had, is that when you advance a round in the tournament, the winners get an extra points say 10, towards their spell book and can add in new spell(s) between rounds but not take any out or swap. For a double blind tournament, you could do 5 points for the losers, even at end there would only be 5 points difference between them if they battled.
Not sure if, points don't have to be used immediately so they could hold for after a 2nd win and have 20 points for 1 spell. Risky since the other player probably used theirs and has something extra they didn't before. Normal rules for costs and limits apply.