Twin ancient entities of gigantic physical proportions, not to mention their massive egos, empowered by tremendous cosmic awareness and energies, came to Earth to judge it. Overmaster transformed six people from Earth-One to combat that world's premier team, the Justice League of America, and discovered the tenacity of the human spirit. Master Summoner returned to Earth-Two after centuries away from it to test it once more, creating various natural forces and agents to combat the Justice Society of America.
Overmaster's six agents were the Cadre of Shatterfist, Fastball, Nightfall, Black Mass, Crowbar and Shriek... possessing the powers of destructive energy, explosive baseballs, light and kinetic energy absorption, gravity control, metaphysical weaponry and sonic screams. A similar group consisting of beings were spawned by the Summoner, his three unnamed henchmen who worked with him behind the scenes the orchestrate the catastrophes that were overtaking the world that the Justice Society had to combat. Their origins are unknown, although other mutated humans attacked various members of the team all around the world, until the Society realized they needed to abstain from further actions which would alleviate the disasters, as Summoner was drawing their own energies into the conflict.