Even after a person's death, this seal was going to exist. As long as a soul lasted, this seal could last.
Not just the seal, but Xu Shan also took more steps. He carved a blood seal on the Empress' back, connecting it to the Soul Seal. If even one link was broken, it meant certain death. He left nothing to chance this time.
Thanks to the seal, the Divine Empress was forced to work for him. It was also one of the two things he wanted her to do in exchange for his help.
As for the second thing, it was simply to take the Book of Devouring from her. But he left that for later since she still needed the Book to utilize the formation and achieve a breakthrough.
"A week?" Xu Shan wanted to finish it faster so he could return to his world, but there was nothing he could do.
The Divine Empress was in much more hurry than him about this formation after all.
