A god may sometimes need to attempt an effect which, while in her purview, is not a practiced or signature ability. In these cases, roll Primal Fire only, spending Essence equal to twice Primal Fire and a point of Willpower. The number of successes will, at the storyteller’s discretion, determine success.
As a rule of thumb: one success on such a roll equals two dice of damage or negates two dice of damage; one success is sufficient for a simple effect such as lighting a cigarette or leaving footprints of sprouting plants; three successes is enough to create a simple effect through a small building or upon multiple people or a larger effect such as a scene of flight, invisibility, taking animal form, etc.
Building-destroying earthquakes and ship-capsizing tsunami are not improvised effects.