Roland widened his eyes and said, "Using dead..."

"No." Agatha interrupted him. "Just as with demons' blood, the flesh should be taken from a living witch."

He heard Nightingale gasp behind him.

"This was the most important secret of the Quest Society. Not long after the experiment began, I left the stone tower of the Holy City. The only thing I knew about the experiment was that it used the blood of weak and old witches, mixed it with God's Stone of Retaliation, and injected it into the bodies of mortals to make mortal's body change." Agatha's tone was a bit grave. "Judging from the notebook you found, this research must have succeeded."

"How much blood was needed?"

"More than half." Agatha's answer saddened Roland. "The blood must come from the same person, otherwise the magic powers contained in it would reject each other and their effectiveness would greatly decrease." She paused. "You guessed correctly. A witch died for every experiment, and mortals could barely survive