There was a planet called Appelax, whose emperor had just died. The laws of the planet said that all the creatures wanting the throne should travel to another world, so, Appelax would't be harmed, and fight until just one survived. The creatures came to Earth on meteors, believing that the Justice Society of America had ended. But, during their jorney, the new heroes showed up.
Martian Manhunter fought a Stone giant. Black canary fought a glass giant. Green Lantern fought a golden giant. Flash fought a fire giant and Aquaman fought a mercury giant. Then, they reunited for the first time to fought a Wooden giant, while Superman, Batman and Wonder-Woman fought a Diamond giant.
The Golden and the fire giant survived and were going to be given to the USA army by the newly-fomed Justice League when agents of the Locus agency invaded the force field buildt by the Green Lantern and stole the creatures, using their DNA do create super-humans that could survive to the invasion being organized by the mental giant, that, instead of fighting another hero, possesed Simon Carr, uncle of Snapper Carr and conection among the JLA and their financiator, that later revealed as the Green Arrow, to prepare Earth to a appelaxian invasion. In the end, The JLA vanquished the Aliens.