Mastery is a measure of a character’s magical power, which governs the potency of each and every spell a character knows. Every spell incorporates Mastery in some manner, either through duration, scope, number of uses, or damage. Whenever a character casts a spell, the character’s Mastery dictates how powerful the spell will be. For instance, most Readied spells give the caster their Mastery in uses when the spell is cast, and Circle spells can measure up to five yards in circumference per point of Mastery. Exactly how Mastery increases the power of the spell is listed in each individual spell description.
Mastery is equal to a caster’s highest level spell school, plus their level in the Willful Trait, plus any bonuses from Occult.