Diesel was burning down a global housing development in Devil's Square owned by Francisco Gracia's father. This naturally caught Stephanie's attention and she busted in to fight the bad guy. She quickly learned he was not intelligent when she teased him about his name, asking if he was diesel as in "Vin or Fuel efficiency" and he responded, "I DON'T UNDERSTAND THAT!" She sheilded herself from his fire and continued to mock his name, suggesting "Napalm" as a better one. He yelled, "NO!" and she noted that he was more about the burning than the talking. Using "Mama Oracle's secret recipe" of ice disks, Steph managed to ice over the villian. She figured out that since his firepumps were connected to his palms, that his blood must be made of gasoline. He broke out of the ice, and she noted that if she cut his "lifelines", he'd bleed out and the fire would get worse.
When he threatened to blow himself and Steph up, she whispered to Oracle that she didn't think Diesel was bright enough to be the mastermind behind this scheme. Then Batman and Robin showed up to crash the party. Stephanie tried to tell them how Diesel's bloodstream worked, but they cut her off and charged in. Soon, Damian found himself on top of a puddle of gasoline with Diesel about to blow both of themselves up. Against Oracle and Batman's warning, Stephanie threw more ice disks at the pair. She managed to put out the fire and send Diesel to the hospital, but she also accidentally froze Damian, much to both his and Dick's consternation.