Mahayana bottleneck!
As the last great challenge before an Immortal Cultivator ascends, it is truly as insurmountable as a moat separating heaven and earth.
Even Cultivators who have reached Perfect Integration may not be confident in breaking through in their entire lives.
If one cannot break through the Mahayana period bottleneck, there's no need to mention surviving the subsequent Heart Demon, Wind Fire, or even Immortal Thunder calamities!
Even Wu Xingzi, one of the Five Sons of Human Race and an entity at the peak of Integration, had no confidence in assaulting the Mahayana level.
That's why Old Meng prepared a portion of the "Five Elements Immortal Water" especially for Wu Xingzi.
If Wu Xingzi could refine this Spiritual Object, he might have a chance of breaking through the bottleneck and achieving Mahayana Power!
But he wasn't confident in surviving the four major disasters that followed, so he refrained from making the attempt.
