@Nikko882 I don't know, the quite simple option of throwing two fireballs in a row seems to me quite heavy. With quickened, haste or whatever. Although it took me a while to grasp it, I think limiting spells is a good thing.
@Nikko882@DonnieDarkmode I agree, it should be more clearly and prominently stated. I also missed it the first time and then needed some time to grasp it well. But I don't think its only about simplicity and quickness. There might come out lots of nasty and munchkenizer spell combos out there without this rule.