Astrium

Also known as the Void or the End, Astrium is the upper division of the Monumidium where the Aidrus dwell. It existed before the formation of Ebdypha. Celestium and Astrium were mixed together between the time when the Eah ruled over the Aidrus, and the time when Heocalan banished the six strongest Eah from the Monumidium.
Astrium itself is a realm of profound darkness, symbolic of existence coming to an end, and of the slowing of energy. It is ruled over by Heocalan, the highest of the Aidrus, none of whom interact with the mortal realm of Domos, and who have found peace with the remaning Eah who dwell in Celestium.