Warbreaker

Warbreaker was one of the first books written by Sanderson, yet it still feels the same as his most recent works. The magic system revolves around “breath” - which has a similarity to peoples souls. The more “breaths” you have drawn from others (by way of them giving them to you), the more unique and powerful abilities you'll have. The way this concept is expanded on, as well as giving and taking breath to others and physical objects makes for a depth of ways to explore this idea.