“Well, it starts small.” She tugged at the hem of her heavy woollen cloak and worried away at it between her two forehooves, looking down at the floor. “Moments, minutes, hours, days. You have a limited time. You have to relearn the spell you had just used as fast as possible. The more powerful and complex, the more of… of you is lost for every second it takes to rememorize the spell.” She glanced at the grandfather clock in the hallway. “It starts with your earliest memory and works up from there.”