"It can't be rushed." Wu Heng smiled, then turned to Sam. "Dean alone isn't enough. The demon blood in your body is actually a great source of potential. This time, I traded Lilith for the souls of ten black-eyed demons. Since angel crystals can refine purifying power, these demon crystals can naturally refine pure dark power as well."
"I didn't give you anything similar before because the demon blood in your body was already unstable. If you were injected with another type of purified power, it could easily trigger a bodily conflict and might even cause you to collapse outright."
"But dark power is different. It matches the nature of the bloodline within you. It may have a slight effect on your emotions, but as long as I keep it under control for you, the negative effects can basically be ignored. Do you want to give it a try?"
Hearing this, Sam unconsciously rubbed his fingers against his palm.
He had always hated the demon blood within him, believing it to be the curse that had killed his mother. But he looked at Dean, then at the box containing his father's sealed soul. In the end, he clenched his fist and nodded firmly. "I'll do it!"
Compared to bringing his father back to life, that little bit of disgust meant nothing.
Over the next hour, Wu Heng locked himself in the room to perform the ritual to refine demon power. A low hum of energy occasionally sounded from inside, mixed with the unwilling howls of the black-eyed demon souls. Dean and Sam stood guard outside the door.
It was not until an hour later that Wu Heng pushed the door open. In his hand was a test tube filled three-tenths full with thick black liquid. His brow was slightly furrowed.