"All of creation cares not whether you live or die."
The Black Stone is the only landmark of note in Shadow's Edge. It was the seat of Samael's power, but has fallen into ruin thanks to corruption after Samael's disappearance. After he vanished, Lilith remained in the ruined fortress for reasons only known to her.
It is the location of the Phasewalker ability, allowing Death to use the green time travelling portals to move between the past and the present at will.