It's just that he doesn't have as many resources as the world itself, and he bears the identity of a Proxy Agent, shackled by Dusk.
If he could survive, he might try to enter the dream realm and make the dream phenomenon manifest into reality, without even needing to create a New World within the dream. He could simply manifest his inner Heaven and Earth while being asleep.
His inner Heaven and Earth is an immensely vast universe.
Unfortunately, the identity of a Proxy Agent renders sleep mostly ineffective when facing calculations.
During this time, Lilith has already eliminated hundreds of tribulation-crossing plans. Each plan seemed feasible at first glance, but in practice, they were of no help to the current situation.
If Zheng Yichen were not a Proxy Agent, these plans would be more executable. Unfortunately, the identity of a Proxy Agent turned all these plans into waste paper.
