To begin the quest, return to the Temple of light and talk to the Defender of the Light with the big yellow exclamation point over his head. He will ask you to defend the wellspring from the Shadow-worshippers. Make your way to the Wellspring and head into the cave, we’ll be retracing our steps from the story quest Hero of Strength, so you should remember what to do – just follow the path through the cave until you reach the area with the three pressure pads.
Walk into the left passage first, and make your way through the cavern and into the pool at the end. You will see a shadow-worshipper perched on the pressure pad you stepped on earlier. As you approach him a pair of bandits will jump down and attack you. Finish them off to cleanse the first pool. Head back to the main switch room. Keep on cruising, straight through the gate on the opposite side of the room and repeat the same process as the first pool.
Return to the central room again, and continue through the final door. As you arrive in the open area at the end of the tunnel, you will encounter a boss-type bandit by the name of Cornelius Grimm. After you fight off a pair of his cronies he will then summon a large group of hollow men to attack you. Defeat the two waves of hollow men he sends at you and he will then decide it is time he stepped into the ring with you. Eliminate him, ascend the nearby stairs and talk to the Abbot to finish the quest.