The Magic-User Archetype (for Karameikos)
Karameikos was crafted to be the stereotypical D&D fantasy realm, and as a result has primarily stereotypical D&D wizards. As a result there's no shortage of ways to build this magical system in HERO. The classic magic system is known for:- verbal (Incantations)
- somatic (Gestures)
- material components (Foci and/or charges)
Also, you need to re-learn / re-select what spells you can cast each morning via spellbooks that is basically the list of spells you can learn and cast. You have newer spells that arise out of research (or learning from scrolls, other mages, or from acquired spellbooks) added to this spellbook.
However, given the HERO points-based, non-class philosophy -- not every mage will be shackled into these exact set of restrictions. In fact, the concept of a magic school or tradition may help very well here.
Magical Learning: Academies or Apprenticeships?
And there might be some rivalry between schools from a given academy, or between different academies as well.
However, there could also be apprenticeships. Depending on where the master or tutor learned his/her magic, the student could have strengths and weaknesses that academy-trained mages lack. And there could also be greater dangers associated with them as well, assuming that part of the approach of the larger academies is to teach magic that works for ALL students, rather than customizing curriculum for each student. Therefore the apprenticeship style of learning could have a more eclectic selection of spell, or a more specialized approach toward things.
And of course, depending on the build, some fighters and thieves may have picked up a minor cantrip here or there...