Millions of years ago, the reason the Immortal Suppressing Hall remained intact under the combined attack of several Immortal Emperors was because the Demon Clan Emperor had laid a formation outside the hall.
Later, after millions of years had passed, the grand formation had loosened due to the erosion of time, which allowed Fang Bai, who was adept at formations, to successfully break it and subsequently destroy the Immortal Suppressing Hall.
However, although Fang Bai broke the formation, he did not completely destroy it, and it could still provide strong defensive capabilities.
Because of the formation's existence, currently only Fang Bai can enter the Immortal Suppressing Hall; other immortals who wish to enter must follow Fang Bai, otherwise, it is impossible.
After all, the formation was laid by a Demon Clan Emperor; even in ruin, it is not something that ordinary immortals can see through.
