The purpose of that great formation was to attach his own soul to the Setting Sun Sect master's body.
In other words, the one currently fighting Li Changge was actually the Profound Demon hidden within this Small World.
He had done this to gather as much information about Li Changge as possible before the final possession.
Only then would he have a chance of successfully seizing Li Changge's body.
This also explained why Li Changge had not sought Xu Changxing's help in the previous simulation.
At that time, Li Changge had most likely still been fighting this unknown Profound Demon within his own body.
Although this Profound Demon's cultivation realm surpassed Li Changge's, Li Changge possessed Sword Intent rarely seen in the world, and his will was no weaker than any Golden Immortal's.
No matter how much preparation his opponent made, he could not possibly complete the possession in a short time.
From what Xu Changxing knew of Li Changge, not only would this possession fail, but even the Profound Demon's own soul would become nourishment for Li Changge.
However, his opponent was a Profound Demon, after all. Such a struggle would inevitably drag on for ages; even ten thousand years would be nothing unusual, and the tide might even turn several times along the way.
At this thought, Xu Changxing suddenly realized that Li Changge's encounter was not merely a peril; perhaps it was also a promising opportunity.
If he could completely absorb a Profound Demon's soul, the benefits to Li Changge would be immeasurable.
Should I help Eldest Senior Brother secure this opportunity?
The thought circled in Xu Changxing's mind for a moment, but he ultimately suppressed it.
Devouring a Profound Demon's soul offered considerable benefits, but that was only true for Heavenly Immortals and ordinary Golden Immortals.