The Saint's Magic Power is Omnipotent (Light Novel) Vol. 4

DARK HEART OF THE FOREST At long last, Sei knows how to control the power of the Saint that resides within her...which means its time to wield it. She must cleanse the forests of Klausners Domain, or her new friends will never again know peace and prosperity. But Seis first foray into the forest depths nearly ends in disaster. While she and the knights await reinforcements from the capital, Sei has to wonder: what if the Saints magic isnt enough? What must she be ready to sacrifice to save the people of Klausner?