Gold Morning refers to Scion's attack on various alternate Earths after being convinced to do so by Jack Slash.  Over the course of four days, his rampage resulted in the deaths of tens of billions of people, possibly far more, before Scion was finally killed.
In his obliteration Scion followed a very specific pattern of reversing the way he had helped people in the past. 
Following his Eastern Seaboard attack he targeted all adults on the coast of Africa, leaving behind 430 000 orphans. 
In Russia he began trapping groups of people in a ring of fire that slowly burned inward.
Within the few hours the total estimated death toll from his rampage went up to 500 million.
↑ 1.01.1 What I don’t understand, is why a blank slate like you would default to doing good deeds, rescuing cats from trees. Why not turn to that violence, as our ancestors did? It drove them, just like it drives the basest and most monstrous of our kind. - Jack's words Excerpt from Interlude 26
↑ The simulated human mind within the entity felt a glimmer of something at that. Pleasure? Relief? Satisfaction? - Excerpt from Interlude 26
↑“United Kingdom, first target struck. Obliteration,” the Doctor said. “Eastern coast of Canada and the United States, damaged, but casualties were a third of what they were in the initial strike.” -
Excerpt from Extinction 27.2
↑“(He's) Following a very distinct formula. He’s reversing what he did at the outset. Saving children, stopping fires. The man who initially gave him the orders is hospitalized, or we’d ask about the instructions he provided. It might give us an idea of what Scion is going to do and the patterns that might emerge in the course of this… experimentation.” Doctor Mother Excerpt from Extinction 27.2
↑“In Russia, his beam started fires. He cut off every escape route, then began setting fires from the outside in. It took him thirty-five minutes to start the fire, and he waited for fifteen minutes while the flames spread and everyone within was cooked. Heroes that attempted to stop the attack were killed.”Excerpt from Extinction 27.2
“We lost just about half of everyone,” Tattletale said. “Maybe more, but communicating’s hard right now. Don’t exactly have an infrastructure.”
“The capes, the civilians. Everyone. Half of Bet’s onetime population is gone, just about. Good news is he’s traveling between possible Earths, hitting major population centers, so the individual incidents aren’t doing so much damage on a relative level. Bad news is he’s traveling between possible Earths.” -  from Cockroaches 28.1
↑“I don’t want to sound negative, but, um, I guess I’m going to sound negative. There are people in third world countries who might disagree, and victims of Gold Morning.” - Excerpt from Interlude: End