Regardless of whether the three teachers successfully killed Duan Ling Tian or not, they would definitely die. Unfortunately, they could only do as they were told because the lives of their families were hanging on the line. Their families had been kidnapped and used to threaten them. If they refused to try and kill Duan Ling Tian, their families would be killed instead.
At that time, a member of the Lone Primordial Spirit Congregation had said threateningly, "Don't think about deceiving us. We have spies in the Myriad Laws Academy. If we find out that you didn't try to kill Duan Ling Tian, your families will pay the price."