West Fortress was a project Moku created to test the real-world application of Pandava. With Pandava, Moku could create anything as long as his imagination could provide detailed specifications. However, this didn't mean he could replicate the exact properties of the original object.
For example, he could create a mutated animal's mana organ in Pandava, but he couldn't give that mana organ the same power as the actual one. Despite using detailed imagination, achieving this level of complexity was extremely difficult.
However, what if he supported his imagination with dragon prana, just like when he used Vivid Dream's abilities? This way, Moku could replicate anything as long as he had enough dragon prana.