The Deep Magic

The Deep Magic was a set of laws placed into Narnia by the Emperor-beyond-the-Sea at the time of its creation. It was written on the Stone Table, the firestones on the Secret Hill, and the sceptre of the Emperor-beyond-the-Sea.

This law stated that the White Witch, Jadis, was entitled to kill every traitor, and if someone denied her this right then all of Narnia would be overturned and perish in fire and water.

However, unknown to Jadis, a deeper magic from before the dawn of Time existed, which said that if a willing victim who had comitted no treachery was killed in a traitor's stead, the Stone Table would crack, and Death would start working backwards. Aslan used this ancient law to save Edmund's life, when Jadis made a claim on his life.

Trivia

 * The Emperor's Deep Magic written on the Stone Table parallels the law given by God to Moses, written on tablets of stone, with Aslan's death mirroring Christ's crucifixion.