There were many reasons for Cain to march into the Emptiness, but there were just as many reasons why doing so would be incredibly dangerous. The main one was that he could not afford to lose himself in that vast expanse.
Although it was true that Adam would not be able to attack the Nine Empyrean Suns Universe anytime soon, the Emptiness presented dangers of its own. It could trap Cain for thousands of years, perhaps even longer, or force him into a battle that damaged the foundation of his body and soul. If that happened, entering the Emptiness would accomplish the exact opposite of what he needed.
Cain might never have entered the Emptiness himself, but he had seen the memories of the Ancestor of the Root. He knew that the Emptiness was a place filled with unimaginable wonders, ancient treasures, and opportunities beyond anything found within the Nine Empyrean Suns Universe.
However, it was also a place filled with horrors.
