Thousands of years ago, on the planet Apokolips, a powerful being called Uxas gained access to the Anti-Life Equation. Desperate to try out this new power to rule the universe, Uxas traveled to the planet Earth with an enormous army, planning to use the weak world as a test run. Unfortunately for him, the native beings of that world, four powerful races known as Humans, Atlanteans, Amazons, and Olympians, formed their own army to protect their world, even calling in help from wizards and the Green Lantern Corps. Uxas managed to activate the Equation, but was defeated by Ares and was forced to retreat with his army, the Equation being taken from him as he did so. A furious Uxas was undeterred and vowed to claim the Equation again, renaming himself Darkseid to show that he was above failure. Meanwhile, the Equation remained on Earth, undisturbed until millennia later.
Return to Earth
In 2015, Apokolips received a message from a human named Lex Luthor, who informed Steppenwolf, Darkseid's uncle and herald, that Earth was undefended, as he had killed the world's greatest champion, Superman alongside Ares. Steppenwolf informed his nephew, who immediately began preparing to return to Earth to reclaim his prize. After a few years, they were ready and set out to Earth. As always, Steppenwolf, being his nephew's herald, arrived first to find the Equation. He succeeded, but tried to betray his nephew by taking the Equation for himself and assembling the Mother Boxes so as to free his mother, Heggra. When he was defeated and slaughtered by Earth's new champions, the Justice League, who also prevented Heggra's return, Darkseid came to the planet himself, fought them for it, and won, leaving the League in despair.
In a dark possible future glimpsed by Batman and Cyborg, Darkseid returned to Earth and killed Lois Lane, lover of the newly resurrected Superman. Distraught, Superman's mind became susceptible to the Equation, and Darkseid used it to transform Superman into his new general, replacing Steppenwolf. With Superman, his army, and the Equation, Darkseid conquered Earth, destroyed the Justice League, and prepared to use the power of Anti-Life to take control of all the planets and people of the cosmos, making Darkseid supreme overlord of the universe and beyond.
The Anti-Life Equation strips its victims of free will and forces them to obey the will of whoever wields the Equation. Nearly any sentient being can succumb to its power, even someone as powerful as Superman.