To Blood Moon, the "Blackstone Trials" was an important step in their plan.
And after obtaining the memories from the Yin specter that possessed Shentu Nantian's corpse, even if Yi Yun did not have a thorough read of the plan, he could guess that Blood Moon had established the Heavenly Dao Union to gather a batch of geniuses. They were fattened like pigs to be slaughtered by nurturing their bodies to be suitable for Yin specters to possess.
The entering of the Heavenly Dao Union was itself a tragedy for the Tian Yuan world's geniuses.
Now, Blood Moon's so-called "not exist in the next millennium" or "unprecedented" Blackstone Trials was to send the geniuses, who were somewhat nurtured, to the extreme Yin grounds, so that they could be possessed by the hibernating Yin specters.
And as they had signed a soul contract, there was Heavenly Dao curse sealed deep in those genius' souls, so it would be difficult for them to even resist.
