What does the witch prepare to do to edmund

When the Witch arrives, everyone around her suddenly feels cold. She points at Edmund and declares that he is "a traitor" and, hence, his blood is her property. She states that according to the Deep Magic written on the Stone Table, the World Ash Tree, and the scepter of the Emperor-Beyond-the-Sea: "every traitor belongs to me as my lawful prey and that for every treachery I have the right to kill."