The Forge of Souls within the Realm of Chaos, as depicted in Total War: Warhammer III.
The Forge of Souls is a location found within the madness of the Realm of Chaos. When a Daemon's physical body is slain, it can surrender its True Name to the Daemonic artificers of the Forge of Souls. The dark bargain thus sealed, the Daemon's crippled essence is bound to a mighty warpmetal hulk. Thus is it reborn as a Daemon Engine construct called a Soul Grinder.[1a]
Legend tells that if said-Soul Grinder can reap sufficient mortal souls from the material plane, the Forge of Souls frees the Daemon from its mechanical prison and returns it to the existence it once knew in the Aethyr. Alas, as with all bargains struck within the Realm of Chaos, this is a debt not easily settled.[1a]
All Soul Grinders are born from the Forge of Souls within the Realm of Chaos.
Many a Soul Grinder has come within a single kill of clearing its debt with the Forge of Souls, only to have ill-fortune see it destroyed, rather than the intended victim. Worse still, if vanquished, the Soul Grinder must sell itself to the Forge of Souls once again, or return to the oblivion it so dreads.[1a]
Should a Daemon remain a Soul Grinder too long, its original identity begins to fade, subsumed into the machine that it serves. After a few millennia of the binding the Daemon's original psyche is gone entirely. Thus can even a Daemon come to be eternally damned, even as it seeks the same fate for mortals.[1a]
It is unclear whether the Forge of Souls is neutral territory between the Dark Gods, or solely controlled by Khorne, as the map of the Realm of Chaos situates the Forge of Souls directly within the Blood God's Domain.