The forces of Xen

Xen. A remote system found in the outlying stars of the galaxy. A system under siege. A system of despair, hope, loss, and gain. A system engulfed in war. This is where we are from. This is what we fight for. This, is our last stand. FOR THE IMPERIUM!

~ Chapter Master Khariiv of the Knights of the Void chapter, upon the impending assault of the Xen System

The fleet based Knights of the Void claim Xen as a recruitment system, its aggressive yet pragmatic people providing the bulk of the Knights' forces, which rarely deploy in anything less than chapter strength.

The Endless Legion arrived on Xen IV in with a Warp Storm. These Chaos Space Marines of Cerberus the Devourer were once one of the Knights of the Void's closest allies, yet their thirst for justice, to right any wrong no matter the cost, left them open to corruption. Thought exterminated, they have returned to wreak havoc upon the Xen system, and all its inhabitants.

The Dark Starz are an upstart Ork clan from Xen V, newly exposed to the warfare of modern space Orks. Led by Warlord Blitzdreg, they have been a menace to the populace of the system for decades.

The Eldar Craftworld Svya'nein recently arrived in the Xen system, its purpose unclear. But they are intent on something, this much is obvious, as Autarch Zeyrose's Wraithships allow nothing to come close.

The 501st Xen Armada are Lord-General Jean Perin's Regiment of Imperial Guard, that first claimed the Xen system in the name of the Emperor. They are held in high regard by all, after having held the system against relentless attack without support for years.

The Necrons of Xen III awakened when The Imperium first landed, but did not attack. Now, centuries later, they are on the march, with an army that could outnumber the Orks of the system.

An exploratory Tau ship, containing Shas'O Kryen and the entire military of the Rys'ka Sept, was pulled into the Warp by Chaos powers, and after months of bitter fighting for survival, they reappeared in the Xen system, well out of reach of any Tau settlements.

If things weren't bad enough, the Tyranid menace has also imposed itself upon Xen, in the form of Hive Fleet Thanatos, a fleet that has just entered the galaxy from the void, and laid waste to most of Xen Extremis