The stone glowed and Karyn's wish was granted, but not the way she expected it to be.
Even though Jon was a zombie, he was still technically human (just a dead human). So, he remained a zombie. But he didn't crave for brains anymore.
He lurched back from the brains he was eating, in disgust. But then got his eye on something nearly as yummy: Karyn's arm. He yearned for her flesh.
Karyn saw the hunger in Jon's decaying eyes and realized what her wish had done.
