It was under the great exodus during the age of Chaos, where the ancestors to today’s Kharadron Overlords fled to the skies, a castaway fleet of frigates in search of a sanctum came across the giant Elgroz. Filled with the well coveted substance “Aether-gold” the refugees first tried to extract it from this sky leviathan, but at the time their tools where not suited to even pierce the transparent skin of Elgroz. Fearing to lose it (and it´s valuable gas) the fleeing duardins decided to settle upon it until they could claim the Aether-gold. This was the start of an unintentional symbiosis.
Elgroz unaware of its new inhabitant living upon it, proved to be both a safe home and a mighty guardian. Even due to the call of Aether-gold, many of the lethal beasts of Ghur avoided Elgroz, fearing its mile-long unescapable paralyzing tendrils. Those foes who tried assaults from above were met with fierce resistance from the great cannons of the duardins, utterly devoted not to let their gas formed treasure get lost. As a bi-product of the increasing cityscape on its body, Elgroz was after many years covered with a thick layer of armour making it into the heavenly bulwark it is now. The duardins accustomed to their new way of life and proud of their unique sky-port have giving up on the thoughts of mining Elgroz of its Aether-gold. Instead they see to it with reverence and care, knowing without each other they are nought.