Biff reached out and grabbed Sarah, and just as he touched her, he suddenly began to glow a bright white. Some people in the room had to cover their eyes. And when the light was gone, Biff was different.
Jon turned and looked at Karyn. They exchanged glances, as they realized that that was the same type of flash of light that the stone made when a wish was granted. Only this time, instead of the stone glowing, it was Biff that glowed.