After the incident with the cultivators deactivating his formation, Yuan continued to spend every moment spreading the poison mist until it was almost time for the gathering at the Undying Fiery Summit.
In just over a month, Yuan had already slaughtered more than seventy million beings within the Abyssal Underworld, leaving him with fewer than thirty million to complete his quest. Of course, he still needed to break through to the True Immortal realm.
Once it was almost time, Yuan retrieved all of the poison mist with the Baneful Abyss before leaving the Abyssal Underground. Although he could've left the poison there to passively grind kills, he didn't want to risk people deactivating his formation while he was gone, as he wouldn't be able to save them in time.
Moreover, he could easily return to this place to finish his quest in the near future, and since he still had to reach True Immortal, he was in no rush to complete it.
