"Illusion That Can Affect A Domain" 

Fooling the domain master was still understandable, but fooling even the domain itself so that it changed even after the domain had been completed and was supposedly not able to change unless the domain master assimilated a new domain? 

That's already beyond logic. 

Axelle broke into a cold sweat as he broke free from the illusion, along with his domain. He knew that if he didn't break free from the illusion soon, his domain would have been destroyed within just a few minutes. 

It was not the domain master who changed the domain under the illusion. The domain master just watched without stopping the change, which led to a complete destruction. 

The illusion would make the domain masters indulge in their dream domain, the domain that they felt the best, and by not doing anything to stop the change in the domain clone, the domain would break.