Science is neither good nor evil, only its implementation is such depending on who discovers the secrets behind it. Rachel Berkowitz and a man named Mousey were brilliant yet demented individuals who wished to bend natural laws around their sinister sensibilities. As such, Rachel discovered the means to access tremendous forces Einstein's Unified Theory while Mousey gathered objects allowing him to harness size-altered radiation. As Blackstarr and Blackstar, the pair of rogues battled teams of heroes, as Rachel's Blackstarr alias was a nemesis of Supergirl and later her cousin Superman, while Blackstar dueled with Law's Legionnaires. Tragedy struck when, consumed with their own power, they were tricked by their adversaries into overextering themselves, to their downfall.
Blackstar had prior to this recruited five criminals to obtain the items necessary for his theories to work: Brain, Falseface, Hopper, Captain Bigg and the Rattler... each battling members of the Legionnaires. While Blackstarr herself worked solo, at the same time she was terrorizing Chicago other villains also attacked Supergirl's city, including the Gang consisting of "the Gang" members Brains, Ms Mesmer, Kong and Bulldozer... as well the Council's Director. Despite their mental aptitude, psychological superterfuge, raw power and brute might as well as cunning... these career criminals could not defeat the Girl of Steel nor the Legionnaires of Law.