 Glinda tells the couple that she isn't powerful enough to destroy Zelena, because she was once a friend.Glinda then tells Snow about a pendant that she gave Zelena and that all of Zelena's magic rests inside of it, but only someone with the most powerful light magic will be able to remove it.Snow realizes that Emma Swan is the only one who can do this, and, since Emma's not with them, the only way to defeat Zelena is to enact the dark curse to get back to Emma.