Gu Shanhai also wasn't confident that he could help Emperor Xuan successfully break through, and the reason was simple: he didn't possess the relevant laws.
Unless he directly extracted the world's laws, which would cause a chain reaction.
As for the laws on him, he could use them, but Gu Shanhai was unwilling. It was just an experiment subject, not worth putting in too much cost.
He's not the only cultivator at the peak of the Heavenly Human Unity Realm; there are many in the Da Xuan Dynasty and quite a few in the Demon Domain, so he need not worry about lacking experiment subjects.
This ancient technique of the Three Strange Books can be cultivated not only by humans but also by the demon race.
Therefore, this ancient method is likely something both human and demon races can cultivate. It's the present-day methods that differ greatly between the two races.
"But then again, why did the world gift the ancient technique to the protagonists Qing Feng and Ming Yue?"
