Defender of the Light
Prize: 750 renown points, Temple of Light Seal.
Talk to the member of the Temple of Light, and he'll ask you to stop the members of the Temple of Shadow from poisoning the sacred water. Go to the Wellspring Cave, where you will check all the water delivering statues. After getting to the first one, kill all foes and the monk by the statue. An identical strategy applies for the other places.
In the last hall, before you fight Cornelius Grimm, you have to take care of some Shadow Worshipper and hollow men. After that the leader will change into a shadow, but you shouldn't have trouble with defeating him. Look out for the Blades spell which he uses. Use Time Control, to avoid his blows and do counter attacks. When the monster falls, go up the stairs and talk to the abbot.