Era beginning/end
Though nobody knows what sparked the divide in the Umbra Army, all are clear of what followed. Hiqra's generals turned against one another - each seemingly vying for the ultimate favour of the Lady of Gloom. The Umbra Army was driven out. Routed and retreating, the commanding officers fled to The Hells, leaving the unorganised troops to be driven into The Abyss. As each of them toppled into the roiling havoc, they swore a blood oath to take their revenge, and to conquer the multiverse for their own. So began The Blood War, which rages to this day.
Historians and acolytes alike have dedicated their live to researching the Relumination, but to date none have unravelled the full sequence of events. What is clear is that Hiqra's generals somehow became divided. Always, Skein had coordinated their strategy, while Zenk had led the army into battle. Their mutual respect withered; driven by some unseen engine, credence gave way to jealousy, and respect became hatred. The fiendish army became divided; the loyal command structure rallied to Skein, while the infantry flocked to Zenk. This reignited the flame of hope in the hearts of mortals; they took up arms and fought. Deities who had watched on helpless for thousands of years saw their opportunity. They lent their strength to the bravest and best of the mortals, and sent what allies they could to join the fight. As The Umbra Army began to turn inward, the forces of Good attacked. United, they stormed The Umbra Army, drove them out of The Material Plane, and pushed them towards The Abyss. In that moment of crisis for the forces of darkness, Skein and his followers retreated to The Hells. Zenk witnessed this betrayal as he battled on the very edge of The Abyss, even as he saw his troops slain or thrown over the edge. He let loose a blood oath, and with a cry of rage turned and leapt into the roiling havoc below, vowing to take revenge upon all the inhabitants of the planes.