Realm of Shadow

"Kulle's blood has opened the portal that leads to the Realm of Shadow, where his body was hidden. I have read of mages accessing these places before, slipping beneath the fabric of reality. But nothing I have read suggested how it might be done; I learned only that it is an endeavor fraught with unimaginable danger. I suppose I should be afraid, but instead I find myself eager to see what lies beyond the portal."

- Li-Ming

The Realm of Shadow (a.k.a. the Shadow Realm) is a zone found in The Terminus in of Diablo III.

Lore
The Shadow Realm is a realm separate from Sanctuary. The Horadrim placed Kulle's body inside the realm after his death. In 1285, his body was retrieved from the realm by The Nephalem, who noted that the realm was perhaps the only thing that made Kulle uneasy.

In-game
In Campaign Mode, it can only be entered after activating both Shadow Locks in The Unknown Depths and The Storm Halls.

It is a dark plane filled with Shadow Vermin, Sand Dwellers and s. Inside, the Horadrim once hid the body of Zoltun Kulle that they could not destroy.

Visually, it is a generic Act II ruins dungeon, except for it is very dark, lit with dim red light, and constantly swept by black, sandstorm-like torrents of smoke. There are two portals inside, the second opening immediately after the player picks up the body.

In Adventure Mode, there is a chance to find a Cursed Chest in this realm, which will be guarded by Maghda herself.