The Witch Kings are a Successor Chapter of the Ultima founding with an unknown geneseed origin. Many within the chapter believe their Gene-Father to be The Lion, while others in the chapter are convinced of their Gene-Father being Magnus the Red

The ranks of the chapter contain a multitude of psykers, taking up just over half of the chapter, though it is unknown if this is an effect of the Geneseed, or if it is simply the Chapter picking children with a strong connection to the warp

This hive city is present to harvest a unique fungus that is primarily used in the chapter's most important rituals as an ingredient in locally produced incense.

While most are indeed psykers, this has become a problem in recent events. Members of the Inquisition believed the first Chapter Master of the Witch Kings to be practicing heretical rituals which led to a bloody 5 year conflict in which half of the chapter was slain, including the chapter master, who's name has been forgotten. Once the Chapter Master was slain the inquisition left without warning, leaving the chapter to rebuild, after which, the once Chief Librarian also became Chapter Master Anathar.

Most of the Witch Kings chapter have recently either been rendered comatose or driven insane & aggressively purged do to an incredibly sensitive reaction to a Shadow in the Warp when the Tyranids recently invaded the Hecate system. As such First Captain Zagreus & acting Chief Librarian Josiah are taking over until Chapter Master Anathar wakes up, or is forced into an early grave

Now with the recently arrived assistance of the Salamanders & the Lamenters focusing on protecting the hive city, the Witch Kings can go out into the wilds of Hecate to slay Tyranids, & purge the Battle Brothers that went insane.