The Vhal are a swarm of living darkness from outside the galaxy. They eat aether. Nobody has ever talked with one.
A star they touch goes dark.
A ship they touch loses its air bubble.
A person they touch becomes a husk, an empty body that walks and obeys.
Aether crystals near them turn black.
The Rim Gates are seven giant stone rings at the edge of the galaxy. The Old Makers built them to hold the Vhal back. The Order of the Last Light keeps a light burning on each gate.
In year 870, a Vhal swarm slipped through Rim Gate Four. It ate the sun of Hush and killed the world. Knights and priests closed the gap. They founded the Order of the Last Light and built Lantern Keep. Hush is now a dead black world under quarantine. Something still moves there.
About 170 years ago the Vhal burned the world of Ashfall. Its ash deserts and glass craters are what is left. The Order runs hospitals and refugee towns there.
In year 1041 the light on Rim Gate Seven went out. Nobody knows who put it out. Since then, ships near the Dark Rim vanish. Some are found drifting with husk crews. Lantern Keep watches the gate day and night.
The Order says the seals are failing. If Rim Gate Seven opens, the Vhal could eat the stars of the Dark Rim first, then move inward. Few people listen. The Dominion and the Union are busy with their own war.
Holy light burns husks and drives back the Vhal. Knights and Priests of the Order are trained for this. Bright lamps keep small swarms away. Nobody has ever killed a large swarm.