The Shadowlands has long been referenced in World of Warcraft lore, but their origins and true nature remain a mystery. One thing is for certain; the Shadowlands are inextricably tied to death and decay. It stands opposed to the verdant spiritual realm of the Emerald Dream, which represents a vision of reality untarnished by corruption and mortal intervention.
For the first time since the release of World of Warcraft in 2004, Shadowlands will involve a level reduction ("level squish"), with player characters at level 120 (the level cap in Battle for Azeroth) reduced to level 50, with level 60 being the new level cap (as it had been in the original game). In what Blizzard has called a "New Game+ experience", newly-created characters will have an updated starting experience on an island called "Exile's Reach", which will introduce them to the game and its systems. For players new to World of Warcraft, characters who finish the starting experience on Exile's Reach will proceed to Battle for Azeroth content, while veteran players who create new characters can choose the expansion experience they wish to play through to level 50, at which point they would proceed to the Shadowlands.
Beings of death are ancient and powerful, and it is dangerous to meddle in their realm. When Odyn peered into the Shadowlands, he saw some of its inhabitants: souls in torment, the husks of the dead, ghostly wraiths with no face, and others with no form, all made of death itself. This was enough to frighten even him. Several races in the Shadowlands, such as the kyrian of Bastion, are souls of deceased mortals who have been transformed to serve a new purpose. If one of these former mortals is killed in the Shadowlands, they die permanently. Other creatures—such as dredgers and stewards—are endemic to the Shadowlands and are naturally born from the magic of death to serve the different realms and help facilitate the process of the afterlife. If one such creature of death is killed, their energy is recycled back into the Shadowlands, and eventually another member of the same race will manifest to take the place of the one that was killed.
After being deposed as Warchief of the Horde in Battle for Azeroth, Sylvanas Windrunner travels to Icecrown Citadel in the Scourge-infested wastes of Northrend, and confronts the reigning Lich King, Bolvar Fordragon. Taking the Lich King's Helm of Domination from him, she tears it in two, shattering the veil between realities and opening a portal to the Shadowlands, Azeroth's afterlife. The Shadowlands have become warped in function during recent times. The Maw, a place in the afterlife reserved for the most sinful souls, is now absorbing all souls.
The final destination of the spirits of the deceased remains a mystery to the priests and philosophers of Azeroth. However, as spells such as [Resurrection] can reunite a dead body with its spirit, and a majority of living creatures from the tauren to the troll shadow hunters claim they can communicate with and call upon the power of the spirits, a widely held belief is that the spirits of the dead remain on the Material Plane — in an immaterial state that can only be altered or contacted through the use of magic.
Adventurers entering the Shadowlands will find the realm of the dead in disarray. In the natural order of things, souls are sorted and sent on to an afterlife realm appropriate to the lives they lived, but starting around the time of the Burning Legion's third invasion of Azeroth, all souls who have perished—including the innocents slain at Teldrassil—are being funneled directly into the Maw. The Shadowlands are starving for anima even as the Maw continues to grow from the glut of fresh souls. Sylvanas Windrunner has been seemingly perpetrating acts to bring about great amounts of death and destruction. In partnership with the Jailer, they have been working toward a common end for some time.