Caged Shura.

Shi Lang was confused when Hou Bing said that the world laws were at work. He asked, "What do you mean when you say that the world laws are the reason? I am just going over to the west and killing demonic cultivators. What is the big deal in that?" 

Hou Bing pecked his cheek hard and drew blood, making Shi Lang grimace. The bird said, "You want to cross the border but do you even know what will happen when you go there and kill enough people? Let me tell you, you ignorant child. 

The western part of the immortal realm is a doorway. If someone manages to go there and kill demonic cultivators they would gain a key to access this doorway. What lies beyond is a world that you cannot even fathom at your level." 

Shi Lang sighed and said, "You mean to say, a secret realm?" 

Hou Bing took a deep breath and said, "Idiot, that is the real world. The immortal plane as you know it is just a cage."