THE RULE OF WORDLY BALANCE

"The Rule of Worldly Balance states that, if they so wish, only one twin can claim their gift , on the occasion of their thirteenth birthday when they pass from childhood into adulthood. But in order to claim this gift, one twin must kill the other. The blood of the deceased is then used to create an elixir. The blood of the twin whose soul is dark shall create the Prophesy of Death, while the blood of the twin whose soul is light shall create the Elixir of Life."