During the early stages of the Limitless Demon Sect's 'Demon Sea Plan,' Demon Emperor Og dispatched numerous experts from the sect to quietly plant many demon god pillars as coordinates in the Netherworld Realm. These demon god pillars served as coordinates for the Demon Emperor Palace to descend upon the Netherworld when the grand plan was initiated, and also acted as catalysts.
The demon god pillar connected the Demon Sea World below to the Demon Emperor Palace above, linking the two together. Song Shuhang was well aware of this entire process... He had replaced the demon god pillar with the Beyond Pillar back then, participating fully in the final phase of the Demon Sea Plan.
And now, it seemed that between the hundreds of floors atop the tomb of the Immortals and the tomb of Ninth Cultivator of True Virtue Tyrannical Song below, there was a need for a pillar to 'connect' them and facilitate their fusion!
