Grand Magister Jurek:
After you have sapped the evil one's strength in battle, apply the crystal to his skin. His soul will be absorbed into the crystal. His mortal body is easily dispatched. Each soul crystal can contain up to 10 souls. A more precise explanation would be that it can contain up to 10 souls with regular usage. I will tell you the detailed story later when you bring back the soul crystal with 10 souls.
Actually, collecting souls for the purpose of bestowing a weapon with a special power is not as easy as it sounds.
What are the precautions to take when collecting souls?"