To master how to host an incarnation ceremony of God's Punishment Army was essential to the pope. When Mayne had taken over the ancient book of God's Punishment from His Holiness O'Brien, it meant that he had been qualified to be the next pope.
Mayne had learned all that was written in the book thoroughly. He knew that to create a man of God's Punishment Army they needed to sacrifice a witch, whose blood would be blended with a God's Stone of Retaliation before being injected into the man of the Judgement Army. Despite that the process had been improved several times over centuries, the essence had not changed—the number of witches limited the total number of the men of God's Punishment Army, and the will of the Judgement Army significantly determined the success of the incarnation.