What are the Are Magica and Elder Scrolls categories? I am not familiar with them.
Ars Magica splits classical magic into five techniques and ten forms, with a spell being primarily of one technique and one form (with possible secondary techniques and/or forms applying as limitations).
The five techniques are: Creo (creation), Intellego (understanding and perception), Muto (change), Perdo (destruction) and Rego (control).
The ten forms are: Animal (self-explanatory), Aquam (water and ice), Auram (air), Corpus (body), Herbam (plant), Ignem (fire), Imaginem (illusions), Mentem (thoughts), Terram (earth) and Vim (raw magic energy, also summoning).
Elder Scrolls magic is all about effects : Alteration, Conjuration, Destruction, Illusion, Mysticism, Restoration. The skills of Alchemy and Enchanting round out the magical abilities.
Another interesting idea could be to have several different classifications depending on the magic tradition (e.g. the mages of the Empire in Warhammer have split their magic into eight colors, but that distinction makes no sense for the orcs - and for good reason, since the imperial codification was designed by an elf who used it to safeguard human practitioners from corruption by chaos by limiting their exposure to different 'winds' of magic). In this case, classification only makes sense for the tradition that designed it, and other traditions might have other classifications that *also* work.
I would really love to do something like this! Unfortunately it is bad enough trying to separate spells out into one set of categories and spell costs, doing it multiple times for different cultures/traditions is just too much work for me.
Practically, you would want to separate by lists and not by individual spells in order to make your work easier, but I agree that, theoretically, each spell should be examined on its own, since two spells in the same list could end up being in different categories because lists don't necessarily follow the same classification logic.
As for traditions, you can always find inspiration in the old standards (of RPGs, at least):
- "asian" tradition would be that of the five elements. Sub-traditions would have different element sets. Think Legend of the Five Rings, for instance, but other RPGs of asian inspiration would help as well.
- "classical" occidental tradition would split between elemental (with four classical elements) and spiritual (with four humours which would likely correspond with the type of spirits - demons, ghosts, the fey, and spirits of man for instance).
- "native" tradition would split between a number of iconic great spirits - think native american (either north, meso, or south native americans, who would have very different 'gods'). In this kind of tradition, the distinction between magic and religion does not really exist since magic comes from the greater entities which are gods.
- I don't really know the oriental (near and middle east, mostly arabian in inspiration) magic split, but I would assume that, once again, religion would play a significant role, albeit in a very different way (probably with a quasi-scientific bias - science, religion and magic were all but thee facets of the same stone).
The core partition concepts depend on the way magic is perceived : is it a quasi-scientific exploration of the unknown, with no relation with religion (medieval occidental alchemy) ? Is it scientific but with a religious foundation (arabic after the dawn of Islam) ? Is it mostly based on a spiritual understanding of the world, and as such, mostly religious (most native spiritual magics, most asian magics) ? Is it mostly material (elementalism or alchemy) or spiritual ? Is magic based on the will of the magus, or on an energy flowing through the world, or exclusively from "beyond" and essentially a by-product of invocation (kinda mentalism/essence/channeling, but most spells would be available to all three traditions, only with different explanations) ?
I think Rolemaster is not the best game to explore those ideas because the structuration of magic is an integral part of the magic system and effects are a by-product of that, whereas a tradition-based system would start with effect, then assign a source according to the belief of the practitioner - leading to multiple explanations of "how magic works" - all "right" since they are able to produce magical effects, and probably all wrong