Phantom Lady possesses a "black-light ray" which operates at Good level. The result is a cone of darkness which average humans cannot see through.
Martial Arts A
The Freedom Fighters * The Justice League of America
Sandra Knight was the beautiful young daughter of U.S. Senator Henry Knight, and was a debutante in Washington D.C. society. She had considerable scientific talent, and in the spring of 1941 Sandra was experimenting with an unfinished black light ray projector that Professor Abraham Davis had been working on before he was kidnapped.
It was during the this period that Sandra spotted two gunmen waiting outside the Capitol Building one evening too kidnap her father. Sandra rushed out of the shadows, attacked the gunmen, and knocked them unconscious. Neither the gunmen nor Senator Knight got a clear look at Sandra, who told them she was a "phantom lady" before she vanished back into the shadows. She then returned to her father, who had no idea that Sandra was his rescuer.
Sandra resolved to continue fighting crime as the costumed Phantom Lady. She told her cousin Ted Knight her decision, which strengthened his resolve to become the costumed hero Starman, who rescued Professor Davis. Once it was perfected, the Phantom Lady used Davis's black ray projector as a weapon. Later, she learned how to use it to make herself invisible.
Phantom Lady became a member of the wartime All-Star Squadron. She was recruited by the mysterious Uncle Sam to join his Freedom Fighters in battling the Axis powers on a parallel Earth called Earth-X. Phantom Lady remained on Earth-X for decades until the Nazis were finally defeated there. She then journeyed to another parallel Earth, Earth-1, somehow gaining the power to become intangible in the process, but she subsequently returned to Earth-X.