The reappearance of the demon race (1)

He had never liked the fourth gravekeeper, who liked to study the demon race. He even felt a little repulsed and always attacked him.

Seeing such a strange thing, he couldn't help but look down on it.

The four gravekeepers stared at the four colors. Their gazes kept changing, and their expressions were extremely serious."This is a special device used to detect air."

"What do the four colors represent?" The chief gravekeeper asked.

His intuition told him that the fourth Gravekeeper's expression indicated that he had discovered something.

The fourth Gravekeeper's expression became more and more serious. "The gray-white color on the top layer is the impurities in the air."

the second layer is Moon White. It's moon essence!

the light green color on the third level is spiritual energy!

The chief gravekeeper nodded slowly,"hmm, why is the last level black?" Are these also impurities?"