Potency describes a spell’s raw power. It is also the measure of a spell’s resiliency, how hard it is to counter or dispel. Even if a spell requires only one point of Potency, the caster might still wish to increase its Potency if he suspects a target will try to counter or dispel it. A spell with Target or Duration as its primary factor (i.e., successes are applied to one of those factors), has a default Potency of one point, making it easy to counter or dispel even if the casting resulted in an exceptional success. (The spell affects many targets or lasts a long time, but has little resilience against countering or dispelling attempts).
Potency is the primary factor for the majority of spells.
If a spell description does not call for successes to be devoted to number of targets (or area affected) or Duration, assume that its successes apply to Potency.
