Last issue, we had a bullet train explosion. Alan Scott is the loan survivor of that. He is confronted by a green fire elemental.
It is quickly established that (1) the explosion was not the elemental's doing, (2) Alan survived because the elemental 'reached in' and saved him and (3) the elemental starts healing Alan's wounds.
Most importantly, the Elemental makes known to Alan that he is being chosen to be be the avatar of the green life force of Earth. The discussion is pretty interesting because Alan asks the logical question. Why wasn't this Earth champion chosen during the time that Apokolips was attacking Earth? The answer is that a champion was not needed because Earth had a 'sun god'. With the 'sun god', Superman, gone, a new champion is needed in his place, the Green Lantern. Superman is a sun god because each of his cells is a powerful soler-powered engine, I got a good grounding on this while reading All-Star Superman.
And thus, the Green Lantern is born.
He needs something to focus his power. He chooses the ring that he used to propose marriage.
Back to the Flash and his encounter with Hawkgirl. The meeting becomes a tussle, but not a serious one, just a test of abilities. The Flash is the more powerful of the two.
But Hawkgirl has more confidence and, presumably, experience.
All of a sudden, everything starts dying.
With the birth of the champion of life in Green Lantern, the champion of death is also born.
I love it that Grundy (Solomon Grundy the zombie not the grey champion) and Green Lantern were also archenemies in the pre-New 52 DC stories.