After a fruitless search, Xu Huo changed his strategy, fully manifesting his spiritual world and adding many more structures on top of the existing foundation.
As he reinforced his spiritual world again and again, the original structure of the book tower became increasingly complex, and its area kept expanding.
The strength and size of the spiritual world both indicate the mental fortitude of the person who created it: the stronger the evolution, the larger the spiritual world's area will be, and correspondingly, the easier it is to craft various complex sceneries.
Once Xu Huo had expanded the existing area by threefold, he finally started to feel exhausted, and thus stopped focusing on its size but began to manipulate the arrangements within the booktower.