This section contains information that needs to be cleaned up. Reason: The death knight realm has already been confirmed to be the Shadowlands. Sylvanas committing suicide from ICC in EoN has already been connected to the Shadowlands. Reword still unclear things, move confirmed things to the main section of the page or remove them entirely if they are already incorporated there.
The Shadowlands will feature five major zones - Bastion, Ardenweald, Revendreth, Maldraxxus, and the Maw. In the center will be the city of Oribos, which functions as the main player hub similar to Shattrath City in Outland in The Burning Crusade or Dalaran in Wrath of the Lich King and Legion. There will be four new dungeons for leveling, four more at maximum level, and a new raid. In addition, a new roguelike "endless dungeon" called Torghast, Tower of the Damned, will be introduced for both solo and group play.
Shadowy Tormentors inhabit this dimension, and emerge from it to torment death knights such as Koltira Deathweaver. The Lich King originally kept them at bay, but after the Knights of the Ebon Blade left his service, the tormentors are now loose upon them. He even appears in the World of the Dead, as he calls it, riding a frost wyrm during  The Power to Destroy.
The Shadowlands can be seen as a shadowy version of the physical world, and can be routinely visited as a spirit when player characters die. Governed by the Covenants, the four ruling realms of the Shadowlands are Bastion, Ardenweald, Revendreth and Maldraxxus (although countless others exist), which serve as the main setting of World of Warcraft's eighth expansion.