then, through a contest, bind them in a fetish of sorts, some obects
that fit the intended purpose and the nature of the spirits. Some of
those fetishes are one-time-only deals: Crush the fetish and the
spirit comes out doing a deal for you, after which it's free to go on
its way. Some are more permanent, giving the character an active
magical ability that he can use over and over again."
This is akin to some of the talisman and fetish ideas I stole from
Shadowrun for the Chlendi. The same idea, but Shadowrun used it to
give your character some setting flavour, but the effect was purely a
mechanical bonus. Consider this stolen.