Originally in my world no one can directly use magic. Magic could only be manipulated through the use of magi-tech devices. In the upper world, a small bottle-civilization either located in the upper atmosphere, a space station, or on the moon (I haven't decided which yet) it's still like that since they are a remnant of the pre-apocalypse civilization. In the lower world, due to being exposed to a high amount of magical radiation for centuries, just about everyone has mutated to be able to absorb, store, and process magical energy as spells. This includes the warriors who use magic to reinforce and strengthen themselves and their body. There's also more traditional mages who throw fireballs and stuff. Finally, those that would be considered traditional battlemages that combine both the internalizing of magic of warriors and the externalizing of magic of the mages exist, but due to their split focus they aren't as powerful in either discipline as a specialist.