[Sabriel hesitates before answering. The key to making the Charter stone was also the key to breaking it after all...but she could trust Saori with a bit of an explanation.]

My blood. The magic I draw from is known as the Charter, created from five Great Charters in my home world. During the creation my bloodline was born, which means the potential of the Great Charter lives in me. In order to use my magic, I need the Charter stone to act as a foundation, a drawing point.