Crusader Kings II: Monks and Mystics adds secret societies, religious orders, and esoteric paths to the medieval simulation. European abbeys carry a sacred mission to preserve holy knowledge and hold secular powers accountable. Eastern sects pursue wayward believers with methods that go well beyond gentle persuasion. Alchemists and underground cults challenge the order that the Church and Crown both depend on, and rumors of dark rituals spread through taverns across the known world.