The First Lantern's three returns to the past timeline had become fixed events, while Perpetua herself had no idea how Batman Dragon would use those three alterations to the past timeline to shape his failed ending. Thus, Perpetua chose a solution that would cause no problems regardless of how things were resolved:
Kill everyone except the First Lantern.
"No! You can't do that!"
Perpetua heard Batman Dragon say this.
No. I'm going to do it anyway.
Perpetua sensed history trying to reshape itself. That was Batman Dragon's doing. He was attempting to change what he had just done—pushing Parallax Hal and Supreme Superboy back into death.
Don't even think about it.
Upstream in the Over-Time Stream (Chapter 957), Perpetua from a few minutes earlier turned her head and simultaneously saw the reality of a few minutes later. Having realized what was happening, Batman Dragon tried to distort history and change the reality in which his two important allies had been pushed into Black Death Emperor's realm of death.
Perpetua saw Batman Dragon appear directly beside the two of them, a Black Lantern ring clenched in his palm as he tried to stop her. But it was useless.
Yes, this history had indeed only just occurred and had not yet solidified in the Over-Time Stream. In theory, it could easily be altered—but the one suppressing this stretch of history was Perpetua herself.
Unless Batman Dragon could defeat her at the moment Perpetua made her move, then...
"You can't stop me." Within the infinitely suspended time of the Over-Time Stream, Perpetua lowered her head. Amid the never-extinguishing starlight, she rode the waves of history and looked down at Batman Dragon.
"So tell me, what meaning does all of this have, Batman Dragon? I am your creator, your maker. Everything should be over.