It wasn't quite as people saw it.
The light people saw was a bit delayed. Their perception didn't catch it, but in that single moment before it appeared, the cosmos collapsed.
It was actively collapsing in a way that could not easily be repaired now. Not because there was destruction tearing it apart, but because this was its fate from the beginning.
The Dark God was the Sacred Abyss Universe's Cosmic Core. The moment he died, it was left incomplete. How was it supposed to thrive when it did not have a brain?
Damien was forced to temporarily take his place and become the center of the cosmos. It was when he made that choice that the light began to spread.
He experimented with his power curiously. The cosmos changed according to his thoughts, giving him absolute control.
'This is why he was arrogant.'
This point of view almost forced one to believe that one was invincible. However, it was just a facade.