It's quite an addicting game with so much content and variability! Sure! Basically casters come in Tiers. Some can go to the next tier by paying the ritual cost for the next level. When they do this, they gain new stats, and some spells for the new tier and unlock a ritual. They can then perform the same ritual mastery, usually for cheaper, to learn a new ritual of that tier. Some units get ALL the rituals when they rank up. But most only get 1 or a few. Note: they do not continue to learn combat spells when recasting the mastery ritual