Hao Ren had been looking for a door in the real world, through which he could safely travel to the Plane of Dreams—there would be no need for troublesome conversion equipment, and longer time constraints while he explored the mysterious world. Plus, he would not be held responsible for the collapse of the Wall of Reality, or the implosion of the Plane of Dreams into the real world. He was looking for the crack, which had existed way before he even began to look for it. To top it all off, it had been safely opened once. Only a crack like that was reliable. The thing he had been looking for was right in front of him.
If the vengeful spirit was like the other unusual creatures—a creature that invaded the real world from the Plane of Dreams—this lilac crack in front of him would then be the passage through which this creature came to Earth.