The goal of the Heavenly Blood Union partaking in the Blackstone Trials was to awaken the slumbering Yin specters. After reading the memories of the masked man, Yi Yun knew that there were hundreds of Yin specters in the Soul Tomb. Some of them had even been lying in slumber for tens of millions of years.
The ancient Yin specters that lay in slumber for tens of millions of years were sealed in a blood rock. They absorbed the Heaven Earth Killing Qi and extreme Yin powers from the Soul Tomb while laying in the long slumber. This allowed them to possess extremely terrifying strength. Compared to those ancient Yin specters, the masked man was a lot weaker.
The masked man was one of the Yin specter executives that were frequently sent out to complete missions. The ancient monsters and ancestors of the Yin specters remained in slumber for cultivation.
If these Yin specters were awoken en masse, Blood Moon's strength would soar immediately.