Origin

Dagny Forrester was created by her brother Cedric Forrester. The process used to create her poisoned residents of New York City including Mary Jane Watson. Spider-Man was able to get an antidote for the poison which she needed to stabilize her powers but he used it to save the city instead. Corona started to physically destabilize. With Harry Osbourne's help, Spider-Man was able to create a new antidote but Corona tried to kill herself. She ended up as a laboratory subject of her uncaring brother.
 
Spider-Man continued to try to help her but he needed a more skilled scientist. Hank Pym and Beast were unable to help due to the court order remanding her to her brother's custody and Spider-Man was unable to contact Reed Richards.

Meanwhile her brother was able to stabilize her physical condition. He implanted her with a bio-monitor to keep her body chemistry stable without injections and without further mutations. He also implanted a feedback loop that made the bio-monitor stimulate the pain centers of her brain if she did not do what she was told.

She was taken control of by an associate of her brother's named Lenny 'The Operator' Flynn who saw a chance for profit. He tried to sell her to the Silvermane Mob but Spider-Man succeeded in foiling the plot and setting her free from him and her brother.
 

Powers and Abilities

Corona has the ability to transmute matter. She can turn solids into liquids or vapors.  She can also turn liquids back into solids. She can also create concussive blasts.

Her powers give her the ability to fly at high rates of speed.