The Nightbringer

Of all the c'tan star gods that once fed upon the fires of the stars, none is more terrible in the mortal imagination than the Nightbringer, whose true name is Aza'gorod. It is the embodiment of death itself, and its dread work in the ancient past has echoed down the ages into the deepest instincts of nearly every living species. During the War in Heaven it carved a path of such indiscriminate slaughter across the galaxy that the fear of death was seared permanently into the racial memory of the younger races, so that even now humans picture death as a robed and skeletal reaper, and the aeldari name it Kaelis Ra, the Destroyer of Light.

The Nightbringer's hunger was its defining trait. Where the c'tan had once subsisted on stellar energy, the Nightbringer discovered that the life-force of mortal beings was a far richer feast, and it fell upon the galaxy's living things with insatiable greed. So consuming was its appetite that it turned even upon the necrontyr who had summoned it into a physical body, and only their desperate pledges of servitude persuaded the star god to spare them and turn its scythe outward upon their enemies instead.

In time the Nightbringer grew bloated and arrogant on the essence of its own kind, having devoured lesser c'tan to swell its might. That hubris proved its undoing when the necrons, led by the Silent King, rose against their masters. Assailed with god-killing weapons forged by the finest crypteks, the Nightbringer was brought low like the rest of its brethren and its vast essence was riven into countless shards, each one sealed within a tesseract labyrinth to be hoarded as a weapon of last resort.

What remains today is but a fragment of that primordial terror, its constituent energies bound within a body of necrodermis and enslaved to the will of a necron dynasty. Yet even a shard of the Nightbringer is a horror almost beyond enduring. The necrons unleash it only when all other weapons have failed, loosing a wraith of cold and shadow that reaps the living in swathes, a splinter of death itself walking the battlefield to remind an upstart galaxy why it has always feared the dark.