How did Orcus become reborn?

...And so it came to pass that these words spoke in wrath dispersed to all corners of the land, proclaiming their message and blasting all minds that heard it. Neighbour turned on neighbour and in sudden fury fathers dragged sons onto the street and there murdered them. The gentle beasts of the field trampled one another and herdsmen slew their cattle to bathe in their blood. The kings and princes of the land fell to fevered imaginings, adorning themselves with armour and weapons, and demanding a throne made from the bones of their kin. Prisoners and slaves were put to the sword and their heads adorned the royal dais. And the kings then sent their soldiers forth into the towns and villages to harvest more skulls for the skull thrones. Every living thing they killed; all that drew breath was culled from the earth, which in turn was fired and the walls tumbled down, so nothing could there live again. When the earth was made as mud by the lifeblood of innocents and wild creatures roamed the deserted lands drinking marrow from the bones of the dead, the kings and princes turned their armies outside their hollow kingdoms to wage war against each other. The armies of all the lands met in a valley blocked by four mountains to the north and four mountains to the south. And there they fell on one another with every weapon, animal and cunning machine that they commanded. The battle raged long as fortune waxed and waned from one army to the next. For eight days and seven nights the warriors of the lands pushed and heaved and stabbed and slew. The kings released their hunting dogs, that harried and bit and gorged themselves on hot flesh. Terrible horsemen, on steeds clad in steel, charged again and again. The death toll was so great that the valley itself filled with blood and drowned those who fought in its depths. The soldiers in battle hungered, and consumed the fallen and drank their blood to quench their thirst, while the kings themselves ate only the flesh from the heads brought to them. As the sun sunk down into the lake of death for the eighth time the battle faltered and stopped, for the bloodthirst that had driven each mortal soul forward had at last been sated. What was left of the armies could fight no more and there came a great wailing from the valley as those few soldiers who could lifted their voice and cried out for release, for victory or for the strength to carry on. A multitude of raised shouts to a thousand empty gods. And none replied. For the true god had heard his servants' cry. And its answer was of bloodlust, power and awesome violence.

From the boiling blood sea rose eight mighty creatures, each with the heads of dogs and the bodies of lions, and each one yoked with great chains of brass. They climbed forth each mountain and behind them dragged upwards a new mountain from the sea, a mountain of bone and skulls that reached fully ten times the height of the eight peaks around it. Upon its sight, the few surviving soldiers of the battle took new heart and rose again from the gore-drenched earth to praise their true lord while the kings and princes threw themselves down on their swords in fear as they recognised the true Skull Throne, of which their own had been the palest imitation. And atop the very summit, the rebirthed-god screamed his name in a birth-cry that echoed and crashed from peak to peak and drove the cowardly near.dead to death even as it strengthened the worthy beyond mortality.

And the name was Tenebrous, our Blood God Orcus.