Iax

Iax was Ultramar's garden world, an agri-world fertile enough to stand with Macragge and Konor by the end of the Great Crusade. Mortarion's Plague Wars ended that. Ku'gath's daemons overran the farms, Guilliman dueled Mortarion on the surface, and Imperial command then burned what was left. It is a death world now, and Guilliman does not expect the rot to lift for centuries, if ever.