This point is difficult for an invincible strongman trapped within the world, but for him, who can travel freely across worlds, it's only of medium difficulty.
The Space Series avatar discovered worlds over the past few months that meet the conditions.
Furthermore, refining a world is also difficult for the common invincible strong. Even if it is a Basic world, it remains vast to an invincible strongman. They can destroy an ordinary planet but cannot destroy a realm. The higher the world level chosen, the more difficult the refining, and naturally, the more benefits gained upon success.
The second point is time. Refining a world takes at least several decades. In the invincible strong's lifespan of several thousand to ten thousand years, decades are short, perhaps just the time for a single retreat. But at a critical time, decades can also be especially long... no one can guarantee that no accidents will occur during the process of refining a world.
