Even among the gods, there were all kinds of characters. While some gods can be very proud, others can be very shameless. Old Kong is definitely the latter kind.
Even though Old Kong was cursed by Old Mao, for fear of being killed by Qin Tian, Old Kong who called himself The Calamity Bearer still told Qin Tian what the key was for.
According to Old Kong, the reason why he and Old Mao were so badly injured was not actually because of their life-and-death battle, but because they tried to remove the power carried by the key.
Even if they were successful, the counterattack from that power actually nearly killed them completely. They were injured so badly that they themselves could not heal their wounds with just ordinary spiritual energy.
Qin Tian and Lan Yueli were greatly shocked when they heard Old Kong's words, but when they heard what the key was used for, they were made even more shocked.