The moment Luke completed Hell Bind, Doomsday sensed the difference.
The rope around its body suddenly became much tighter, and the initial slack disappeared; it was like an unbreakable net that was firmly wrapped around it.
An ultimate skill that Luke would use at a time like this naturally wouldn't be a simple one.
With his Roping skills and Ultima's calculations, there were hundreds of optimal methods effectively targeted at most living creatures — especially humanoid ones.
Once Hell Bind was completed, it was no longer a rope that the bound person was dealing with, but a huge net with the greatest distribution of force.
The bindings had to be untied with special and precise movements and skills. Otherwise, the bound person could only break free with more than ten times the brute force.
Using force in the wrong places would just cause the rope to tighten even more.