The mark on his forehead flashed briefly before a large black blanket covered a part of the sandstorm. Then the black blanket receded into his Mental World, carrying everything that it had covered with it into his Mental World.
After taking a bite out of the sandstorm city, he took another one. Then another one. And a third one.
This black blanket is not his Mental World. It is an ability of his Mental World to take things from the physical world and put them into his Mental World. Every rank 5 cultivator can do this.
But the Mental World of rank 5 cultivators is fragile. They can't just put anything into their Mental World, just like mortals just can't put everything into their mouths.
Most of the things in the world are things that aren't compatible with their Mental Worlds and will cause them injury when introduced into their Mental World. This injury will remain and won't heal until they remove the foreign object from their Mental World.
