The First Gods War

When Saelen discovered they could gain more power through the worship of the High Elves, they started the Cult of the Creator. The Celestial presented themselves as the Creator of the World, and the only God worthy of worship.
  The High Elves began to revere Saelen, and as expected, the Celestial became more powerful with each new believer.
  Feeling secure in their newfound power, Salen started a campaign against their siblings in order to gain dominion over the Immaterium. What Saelen didn’t plan for, however, was that the other Celestials eventually allied in order to take them down.
  Faced with an aligned opposition, Saelen thought to find allies, not in other Celestials, but amongst the mortal High Elves. Their influence over the Immaterium was already collectively strong enough to influence the tide of the conflict, and with a little boost, could prove invaluable.
  Saelen thus offered the Elves a deal:
  They could remain simple worshipers, live and die a simple life.
  Or they could ascend to Sainthood and become their Warriors and Protectors of the Elves.
  The Angels were thus born, from the devotion of the Elves and the glory of Saelen. These Elves were mortals no more, and could walk both the Earth and the Immaterium.
  With their new army fighting for them, Saelen started gaining the advantage again.
  The other Celestials eventually had to concede the helpfulness of mortals. If they could not only gain from their worship but also make them fight in their stead, eventually one Celestial could take the upper hand on all the other.
  The first one to make a move on the High Elves was Kraal. He saw that not all Elves were keen on following the strict rules of Saelen and some were horrified to see their family so freely giving themselves to the Goddess.
  Kraal also sought doubt in the minds of the Elves: if the Goddess had siblings, why shouldn’t they also be worthy of worship? And did She really create everything?
  A contingent of Elves decided to start worshiping Kraal instead. He offered them His blessing and granted them strength beyond their dreams. However, the blessing mutated their bodies and they became what are now known as the Orcs. They were bigger and stronger, but their ability to influence the Immaterium directly was reduced.
  Frustrated by this, Kraal saw another way to take the advantage. If they killed in His name and put the fear of his wrath into the Elves’ mind, then the result would be the same. His power would increase, and that of Saelen’s would decrease with each of Her follower’s death.
  The Orcs started a war against the High Elves, looking to butcher them and sacrifice them in Kraal’s name.
  Other Celestials followed in Kraal’s footsteps, trying to get a foothold on Tharan and build their own army of worshipers.