Demons of the Ruinstorm
The Ruinstorm was a warp storm that appeared during the Horus Heresy, engineered by Primarch Lorgar of the Word Bearers to isolate loyalist forces. Unleashed by first chaplain Erebus during the Battle of Calth, the Ruinstorm was further grown and perfected by Lorgar due to the bloodshed he unleashed in the Shadow Crusade. The Ruinstorm birthed uncountable numbers of Demons empowered by the misery of the loyalist forces.