Confusion

There were many Chaos creatures imprisoned on Dry Origin Mountain. Meng Chuan also wanted to kill a peak Seventh Tribulation Chaos creature, but he had made many attempts. His Essence Soul avatar was forced to dissipate every time. If it didn't dissipate on its own accord, it would be devoured by the Chaos creature.

It wasn't that he didn't want to defeat them—he just wasn't strong enough!

According to the intelligence provided by Senior Brother Thousand-Hands, one had to reach the half-step Eighth Tribulation realm before they had a chance of killing a peak Seventh Tribulation Chaos creature.