"Planning A Domain Explosion" 

The world union would not want to sacrifice other people except for the transmigrators, so the first step of the plan was still to explode the souls of the transmigrators. 

Then, the explosion that came from the souls of transmigrators would pierce through space and time, accurately blasting the nearest object in the fourth void— the abyss tunnel. 

Because the tunnel itself was made of the law involving space and time, only such a 'bomb' could destroy the tunnel. 

Or, people could also blow up their own domain clones, but just several domain clones would not be able to destroy the abyss tunnel compared to the soul explosion of hundreds of transmigrators. 

Unless the domain clone was as big as Axelle's domain.