"This... monstrosity. This was the first thing that truly made me fear death. The first time the skies turned that eerie crimson and the galaxy shrieked in horror, I truly realized that we are not guests in this forsaken realm."
The Nightmarelunen is one of the seven Deagami Nebulis and has one of the most pronounced effects.
The Nightmarelunen is a twisting nebula, deep crimson in hue, with helical strands of black dust surrounding its outer edges. Inside it are many worlds bathed in its eerie light, though none have ever produced life. It spans only a few light years in diameter, but the light can be seen from even outside Lunen Tsuki, along with the other Deagami Nebulis. Over the course of a few standard days, the Nightmarelunen can be observed "pulsing" as it grows brighter and dimmer. It is dimmest immediately after an active period ends and reaches full brightness around 156 days later.
While the crimson realm may seem foreboding through appearance alone, its active state is something to behold. The nebula becomes active once two conditions are met. The first is that it has been over 156 days since it last activated. The second condition is that a threshold of sapient beings are within it. These conditions are usually met by young and reckless citizens doing tests of courage. Once the Nightmarelunen activates, a sort of spatial boundary forms, appearing as a somewhat dark veil around the nebula itself. Nothing can enter or leave. Once this happens, all of Lunen Tsuki turns a blood-red shade and begins shaking. Quakes rattle every star and planet in the now bloodied bands of gas and dust as the core of the galaxy wails in agony. Ten random calamities befall all sapient beings within the veil of the Nightmarelunen. These are usually lethal, but any survivors are rewarded for living through the calamities with severed pieces of their deceased loved ones.
The Nightmarelunen has been around for many millions of years. However, like the rest of the Deagami Nebulis, it does not dissipate into the rest of Lunen Tsuki. Instead, for most of its history, it has drifted around the cerulean realm, waiting for sapient life to foolishly enter its domain. Once, it is thought, a star with a budding primitive civilization fell into the maw of the crimson abomination. The Nightmarelunen awakened for the first time in millions of years and unleashed its fury on the galaxy. The explanation was crafted after similar ancient prehistoric records from all three native sapient species described a night where the skies turned red and began shaking. The violence and terror of that night was a special occurrence, but the unique horror of it has become a semi-regular happening since the arrival of the now sprawling Theocracy of SIlverstar.
Ever since the Theocracy began expanding throughout the galaxy, encounters with the Nightmarelunen have been happening more often. The safe period that exists after an active period is one of the only things preventing the cerulean vortex from being consumed eternally in the blighted glow of the Nightmarelunen.