Casually Response.

Masses of black clouds hovered about without dispersing. The condensation of the nearby Sound Beasts' yin aura had created those clouds.

The Sound Beasts running out from the Sound Beast Mountain brought heavy yin aura along with them because the Sound Beasts' bodies contained the yin aura. The yin aura was the power resource of the Sound Beasts, the most primary source allowing them to survive.

The whirl originated from Shi Yan had a powerful gravitation. The whirl's existence made the yin aura hovering around those Sound Beasts' bodies fly out and then went back to the center of the whirl. After that, the yin aura turned into the yin power absorbing into Shi Yan's body and finally becoming the Yin Pearls on his chest.

The Black Formula was excellent. It unexpectedly had a terrifying power to take in the yin aura from the surrounding Sound Beasts.