Summoning allows a Character to call a Spirit to ones service.
To summon a spirit a character first determines the kind of Spirit and the Force of the Spirit to summon. The Summoning Test is an Opposed Test between the summoners Summoning Skill and the Spirits Force. The Spirits Force (Force/2 for Watchers) determines the Duration of the Test in Seconds.
The Summoner may chose, right after summoning the Spirit, to exchange one or more services for optional spirit powers.
Summoned Spirits only stay till sunset/sunrise (depending on the summoning location) or next new moon/full moon (if that happens earlier, in case of being on the poles) at which point they vanish to their Meta Plane with all Services spent.