The Dream Realm is a realm which can only be accessed by the nobles who are able to accomplish the Dream Challenge. It is accessed by using the ancient and nearly forgotten art of Dreamwalking. In the past, the Dream Realm was a renowned gathering place of the Nightmare Knights for their attacks, plannings or simple regroupings. They were able to modify the realm by creating the Chamber of Dreams in order to better traverse it and reach another destination in the conscious world. This way they could make Dreampaths directly connecting two locations.
During the war with the Ruthless Seven, the demons had uncovered parts of Knights' secret, and were able to take control of several pivotal points in the realm, including the chamber, thus cutting the Knights off from each other. Now the realm is mostly void, but it is still the home of the last Dreammaster of the Nightmare Knights and also the only surviving teacher of the arcane magics of necromancy, which would welcome you to the dreaded order of the Brotherhood of Bones.
To prevent unwise people from joining the esteemed ranks of the Nightmare Knights, the ancestors of this heroic order have created a test consisting of a few riddles, which came to be known as the Dream Challenge. Only those who can master this challenge may apply for joining the ranks of the Nightmare Knights.
This place is also where the Dream Realm Library is located.