Ye Xiao could have easily killed Xing Ming, Tian Liang, Lu Family's head, and other elders of big families from three countries by using Soul Destruction, but he did not choose to do so.
He wanted to see how much his fighting prowess has increased and how well he could face someone at the Martial Saint Realm without relying on the abilities he has gotten from the three dragons.
Now, he could finally estimate his fighting prowess. He was confident that even if he did not rely on the abilities of the three dragons, he has the power to face or even kill an Eighth Stage Martial Saint Realm martial artist.
Xing Ming was at the Second Stage of the Martial Saint Realm while the Lu Family's head who was sucked inside the Thunder Fire Tornado and burned alive was at the Third Stage of the Martial Saint Realm.