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.
Ascend the Tower of the Damned: at the heart of the Maw lies Torghast, Tower of the Damned, a cursed otherworldly prison where the wickedest souls in the universe are locked away. Highly replayable and inspired by roguelike games, heroes are invited to explore its ever-changing halls and chambers and do battle with the minions of the Jailer, Torghast's vile ruler. Those who brave its trials can claim legendary treasures and help free the heroic spirits wrongfully trapped within.
Alpha Beta PTR Vanilla 1.1.0 1.2.0 1.3.0 1.4.0 1.5.0 1.6.0 1.6.1 1.7.0 1.8.0 1.8.4 1.9.0 1.10.0 1.11.0 1.12.0 Burning Crusade 2.0.1 2.0.3 2.0.4 2.1.0 2.1.2 2.2.0 2.3.0 2.4.0 2.4.3 Wrath of the Lich King 3.0.2 3.0.3 3.0.8 3.1.0 3.2.0 3.2.2 3.3.0 3.3.3 Cataclysm 4.0.1 4.0.3a 4.0.6 4.1.0 4.2.0 4.2.2 4.3.0 4.3.2 Mists of Pandaria 5.0.4 5.0.5 5.1.0 5.2.0 5.3.0 5.4.0 5.4.7 Warlords of Draenor 6.0.2 6.0.3 6.1.0 6.2.0 Legion 7.0.3 7.1.0 7.1.5 7.2.0 7.2.5 7.3.0 7.3.5 Battle for Azeroth 8.0.1 8.1.0 8.1.5 8.2.0 8.3.0 Shadowlands 9.0.1
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 four zones that comprise the Shadowlands are ruled by "Covenants", similar to the Class Orders introduced in Legion. Each Covenant will have its own campaign, similar to the War Campaign in Battle for Azeroth, with gear specific to the faction and abilities both universal and determined by class. The four covenants are the Kyrian of Bastion, the Night Fae of Ardenweald, the Venthyr of Revendreth, and the Necrolords of Maldraxxus. Players experiencing the Shadowlands content for the first time will need to reach level 60 before they can choose to pledge themselves to a Covenant, while alts are able to do so at the start of the Shadowlands content.
In the opening cinematic, Sylvanas shatters the Helm of Dominion, breaching the veil between the material realm and the Shadowlands, an ancient dimension where the dead coalesces for judgment. Sylvanas' actions have upset the natural balance between life and death, and it's on players to enter the Shadowlands itself and repair the cycle before it is too late.
Sometimes, the spirits roam the Shadowlands without resting. It can be because their resting place wasn't complete, because of a battle in their resting place or because of the corruption of their resting place. To bring eternal peace to the souls, it is needed to destroy the source of corruption or by making a ceremony with items such as [Tuskarr Ritual Object]. A spirit in the Shadowlands can, with enough power over other souls, tear a hole into the living world once they are strong enough. This is how Jin'do returned to Azeroth.