Originally Posted by
noparlpf
For spells, I think the 3.X spell descriptors would be a better existing system to split things up with. Like, Fireball would require that you know at least one [Fire] spell each of second level and of first level. Maybe give different spells from same schools a "discount", like Lightning Bolt only requires one lower-level [Electricity] spell, of first or second level, if you know other Evocation spells of each second and first level, because you have some practice casting Evocations and some casting Electricity spells, so you combine your knowledge and "skip" some of the Electricity training.