The Shadow Ruins are where the Rod of Divinity (A Relic of Power) is at. The shadow lord is guarding it in a pentagonal room. He has also captured a knight that tried to defeat him, and has imprisoned him for many long years being tortured for all of eternity. He tells you that the only thing that can kill the shadows is the sword, Shadowslayer. When you acquire the sword you must kill his torturers and free him. Then you must fight the shadow lord and defeat him several times until you have killed him five times. then put the five shadow stones you get into the statue to make him vulnerable to you. The Rod of Divinity has strength against shadows, so it is recommended that you use it to kill him.