The Roaring Blades are a Traitor Imperial Army formation dedicated to the Chaos God Slaanesh. They have close ties to the Emperor's Children Traitor Legion, whom they served with before, during, and after the Horus Heresy, in a similar style as that of the Prospero Spireguard that served the Thousand Sons Traitor Legion. They were originally known as the Righteous Blades before they fell from grace and turned against the Imperium.
Long ago, during the era of the Great Crusade, the Righteous Blades were one of the most decorated and respected infantry units in the Imperial Army. Vassals of Fulgrim, the Righteous Blades provided infantry support for the IIIrd Legion. The Righteous Blades fought on countless worlds in the name of the Emperor, and won several victories. But when the Emperor's Children turned Traitor and joined the Warmaster Horus in dedicating themselves to the Dark Gods of Chaos, the Righteous Blades followed suit, pledging their souls to the desires of the Lord of Pleasure. The Imperium lost a proud band of warriors that day, but the Righteous Blades lost their souls, becoming pleasure-addicted acolytes of Slaanesh. These Emperor-forsaken Heretics then became forever after known as the "Roaring Blades." It is believed by Imperial intelligence that the nervous system of the traitorous troopers of the Roaring Blades have been altered by the Emperor's Children. As a result, their bodies react to pain as if it were adrenaline, meaning that wounds sustained battle only drive them further into violence.
- Scouring of Vernalis (Unknown) - During an unknown point in Imperial history, the Roaring Blades were used by the Emperor's Children Traitor Legion to help invade and conquer the Mining World of Vernalis. This led them into direct conflict with the Imperial Fists Space Marine Chapter. In due time the Imperial Fists were able to cease the invasion and neutralize the Forces of Chaos on Vernalis, including elements of the Roaring Blades.
The Roaring Blades have a preference for close combat with bladed weapons of various kinds while screaming out in ecstasy throughout a battle. They also recruit and enslave new members from any and all worlds they encounter, making use of both standard heretics and mutants. They put little to no effort in maintaining a rank and file structure to their armies.
- Sons of Dorn (Novel) by Chris Roberson, pg. 86, 93-94