If you played Dark Souls 2's multiplayer beta, you might have encountered this boss before--except, back then, he was called Mirror Knight. He's a slow, lumbering enemy, but has some decent range on his sword attacks.
If you get too far away from him, watch out--he'll cast a volley of lightning balls your way, which you'll need to roll dodge to avoid. When he slams his shield down into the ground, get ready--he'll summon another actual player to help kill you if you're playing online, or an AI minion if not. Need additional tips? Check out the video above.
For more help be sure to check out our complete Dark Souls 2 Boss guide.