Luminarium

The Luminarium is a location in The Ancient Gods, Part One, the first expansion for Doom Eternal. Located within the Holt, an expanse on the edges of Urdak, the Luminarium was constructed by the Seraphim to serve as a dwelling for the Father; it also houses machines that are capable of manipulating the essence of life.

History
After the Seraphim were stripped of their wings by the Father following the Battle of Isonkast, they built the Luminarium as an act of atonement to serve as a dwelling for the Father. Within the Luminarium the Seraphim constructed numerous works, including machines capable of fusing a being's consciousness into a life sphere as well as reconstituting life spheres into physical forms; these machines are described as existing just outside of reality, tapping into mysterious primordial forces called the Engines of Creation, and are considered far superior to Hell's soul-extraction devices.

To prevent the Seraphim from seeking further power, the Father commanded that they serve all who reach the Luminarium equally, regardless of their alignment or motives. No blood can be spilled within the Luminarium; were a being to do so, then they would lose access to the powers of resurrection granted by the Luminarium.

After the Father withdrew from the physical world to prevent the Dark Lord stealing his power, Samur Maykr brought his life sphere to the Luminarium; during this time, Maykrs would travel to the Holt to meditate before meeting the Father. After Samur stole the Father's life sphere from the Luminarium to transport it to the Ingmore's Sanctum, the Maykrs lost access to him and the path to the Luminarium became unattended and overgrown.

The Ancient Gods
During The Ancient Gods, Part One, the Doom Slayer acquires the Dark Lord's life sphere with the intention of taking it to the Luminarium, where the Dark Lord can be forced into physical form and then destroyed; as expected, when he reaches the Luminarium the Seraphim unquestioningly accept the sphere and reconstitute it, despite the Father's warning that the consequences of this action are irreversible. When the Dark Lord's physical body is restored, the Slayer tries to shoot him but inflicts no injury, as the Dark Lord points out that no blood can be shed within the Luminarium.