Heed is a dead world in the Markayn Marches of the Calixis Sector and a battle site of Angevin’s Crusade. The arch-traitor Feldrus Xorth was responsible for the destruction of Heed during the Crusade’s first years within the sector. Renowned for the noxious firestorms that pepper its surface. Despite the world's dead nature, a successful and renowned research station of the Adeptus Mechanicus is in orbit around it: Iridium Eta Rho.