Hm, apart from resting I could also think of some kind of other purge-mechanics for the spell cool-downs between the fights. For example, it could cost you 100 gold coins to remove one cool-down turn from the spell, 200 coins to remove two cool-down turns, 300 for three turns etc. Or it could be tied to your life energy, so that you have to sacrifice 5 health points for one cool-down turn removal, 10 for two and so on.
