Typhon Primaris was a jungle-covered Imperial Feral World found in the Sub-sector Aurelia of the Korianis Sector and was one of the primary recruiting grounds for the Blood Ravens Space Marines Chapter. Its population primarily consisted of a small number of human settlements and several klanz of Feral Orks.
During the events of Dawn of War II in the late 41st Millennium a Craftworld Aeldari Warp Spider Exarch was provoking the Orks to attack Imperial outposts and villages, and the Space Marines of the Blood Ravens Chapter intervened. However, unknown to them, Typhon Primaris had been infested with Tyranid Genestealers and some plants and animals became mutated by the Tyranid organisms, killing the human settlers' livestock.
Soon after, a Tyranid splinter of Hive Fleet Leviathan appeared over the lush planet, drawn by the Genestealers' psychic emanations, threatening to engulf the entire star system, though this Hive Fleet was defeated by the Blood Ravens in the course of the conflict known to that Chapter as the First Aurelian Crusade.
Ultimately, to deal with the ongoing Tyranid and Chaos threat approximately a standard decade later, an Exterminatus action was carried out upon the world by an Imperial Retribution Fleet under the command of the Inquisition's Ordo Malleus on the orders of the Puritan Inquisitor Adrastia during the Third Aurelian Crusade, leaving it a barren, blasted Dead World.