Talion was fighting you, who claimed to want to save middle earth by getting rid of sauron and Celebrimbor, but when he saw the Nazgûl ring you stole from one of the unnamed nazgûl, he knew you'd succumb to the witchking, and that you'd fail in your goal. What he didn't know is you have been holding onto the ring ever since you sacrificed yourself when you were on a journey with Bilbo Baggins and the company

"I shall not let you do this!" He yells, trying to block your every attack