Spirit Contracts and Magic
On the Steve Jackson Games Discord server, a question came up. A poster wanted a magic system that represented negating with spirits for various effects. GURPS has Spirit Assisted Magery and other options, mostly in GURPS Thaumatology but these did not quite meet his expressed need.
So here is an initial run at addressing that. Note that there are many ways to handle things in GURPS and it gives GMs a good foundation to work out options and come up with specific things to address their needs for their campaigns. So this is just one way to do it and by no means the only way and has not been play tested by me. But it’s a fun exercise and interesting idea, so here goes.
Book/Path Magic, Divine Favor, GURPS Magic, Realm Magic, Ritual Path Magic, Sorcery, Syntactic Magic and more exist. I think Book/Path is the best fit here. Default spells take longer to cast which can represent negotiating time. Divine Favor would be good if each spirit was a Patron or if they were taken collectively as a single Patron but this implies an existing good relationship.
Book/Path as Spirit Bargains
I think the Effect Shaping variation is best here, though Energy Accumulation could work too.
Effect Shaping means the result of the negotiation is from a single die roll. Energy Accumulation provides “energy” over a period of time and repeated rolls so could be more of a :slowly winning the spirit over” approach. I just recommend Effect Shaping as a cleaner and less convoluted method.
Ritual Magic represents a knowledge of spirits and rituals for entreating them for power. So we keep the core skill, perhaps elaborating on it for the setting and different cultures may have different specialties representing the difference between kinds of spirits.
What I would change though is the Paths or Books. Each Book/Path should represent either a specific powerful spirit (say a book for a named demon outlining common deals it is known to make) or a Path for a collection of related spirits (Fire spirits, ghosts, Djinn, Nature spirits, Fairie, etc.).
Assign and create new rituals to appropriate Book/Paths, many rituals will be in multiple paths as is the current case. In this case each ritual is pretty much a boilerplate contract for specific services rendered. The ritual may be all that is required of one or both parties or it may involve something more from one, especially the magician. Perhaps a sacrifice or promise to do something in exchange for the service provided by the spirit. This could lead to some interesting spells, though each spell would need some work by the GM to come u0p with just what the magician has to do to honor their side of the deal.
I would put the Fetish ritual into every Path and many Books though. Or rather a variation on it that only applies to the appropriate spirit. This represents a prearranged deal and allows casters to have some effects be very quick because the deal was already made.
Alternatively create a new ritual for this and charms are effectively tokens that trigger the already bargained for effects.
Using this in a Setting
I could see using this in a setting, though I would want to make up new rituals and outline spirits to help me formulate the Paths. My upcoming supplement GURPS Template Toolkit: Spirits as lenses for various types of spirits with a vey brief description of personality and other traits so that would help a GM using this system but ideally that GM would come up with more detail.