Designing a contractual magic system?

[dataweaver]

I don't know if this helps; but GURPS Spirits described three kinds of spiritual magic users: there were priests, who were defined as servants of godlike spirits; there were shamans, who were defined as interacting with spirits on a more or less equal footing; and there were sorcerers, who had spirits serving them. In order to avoid unfortunate implications, my own approach to this has been to categorize spirits into three broad classes: gods, spirits, and essences. Essences are like spirits in most ways, except that they aren't sapient; and many of them aren't even sentient. They're like the flora and fauna of the spirit world. Priests serve gods; shamans deal with spirits; and sorcerers control essences.

If you want, you could break it down a little bit further, splitting sorcerers into sorcerers and wizards, where sorcerers deal with spiritual fauna (sentience, but no sapience; spiritual pets that the sorcerers train and command) while wizards harvest and use spiritual flora (no sentience; in practice, there's little difference between this and “manipulating impersonal magical energies”).

This could be thought of as a framework for a “contractual” magical system, with wizards, sorcerers, shamans, and priests representing four different kinds of “contracts” — though in the case of wizards, it's more of a lack of contracts.

You might even throw “psychics” into the mix, where a psychic operates on the basis of “human spirits”: astral projection is the power to separate your spirit from you're body; possession is the ability to force your spirit into someone else's body; telepathy and mind control would be the powers to directly communicate with and manipulate other people's spirits.

In fact, you might consider making psychic powers the basis for this magic system: a psychic develops his own spirit's ability to manipulate fire and calls it pyrikinesis; a wizard or sorcerer gathers and directs fire-aspected essences and thus performed pyromancy; a shaman bargains with fire elementals; and a priest serves a god of fire. But whether it's a god, a spirit, a “spiritual fauna”, or even a “spiritual flora”, its ability to manipulate flames is exactly the same as the pyrokinetic's ability to do so; the only difference is that the psychic manipulated the flames directly; all of the others get something or someone else to do so, either by praying to them (in the case of gods), bargaining with them (in the case of spirits), commanding them (in the case of “spiritual fauna”), or simply using them (in the case of “spiritual flora”).

Though in a sense, all five types of “magic users” in this system would technically be psychics: wizards would need to develop their own spirits to be able to detect and interact with “spiritual flora”; sorcerers would need to develop their own spirits to be able to summon, bind, banish, and ward against “spiritual fauna”; shamans would need to develop their spirits to be able to sense and communicate with spirits; and while priests wouldn't have to develop any special spiritual abilities of their own, their gods would likely require them to develop their spirits in other ways, such as developing appropriate codes of conduct in order to turn themselves into more effective channels for their gods' powers.