Four sons of Horus Nekhen. In Spells 112 and 113 of the Book of the Dead which have their origins in the earlier Coffin Texts Spells 157 and 158, it is described how Horus has his eye injured, and because of this is given the sons of Horus: The injury of Horus's eye is part of the myth cycle known as the Contending of Horus and Set recounting how they fought over the crown of Egypt. In a unique illustration in the tomb of Ay the sons of Horus are shown wearing the red and white crowns as the Souls of Pe and Nekhen,
The Horus Heresy (novels) Heresy and "Warhammer 40,000" canons; still other non-series Horus Heresy material has been eventually incorporated into the work. A significant development was the 2012 initial release of the "Horus Heresy" miniatures wargame expansion, which repositioned the concept as a foreground element within the "Warhammer 40,000" gaming system while highlighting the importance of the Horus Heresy to Games Workshop's product lineup and the related universe. The expansion is reputedly developed in coordination with the book series, and includes new material and information about the Horus Heresy and the fictional universe; it joins the series and other works as an authoritative source