The Demon Realm is one of the Team Instances you can go to. You can either invite people to be on the team with or you can let the system find a team for you. There's a chance that you can win a Frost Necklace, Odin's Necklace, and a Soul Chest. On the hard mode, you can win Frost Necklace, Odin's Necklace, and Warrior Certificates. The boss of the Demon Realm are Big Ape 1 & 2.