The Nine Heavens Blazing Thunder Formation was a true ninth-tier formation. It could trap and battle Tribulation Crossing Immortal Venerables; once Mahayana Cultivators entered it, their chances of survival were slim.
However, that referred to the Nine Heavens Blazing Thunder Formation at its peak, with a formation master presiding over it. Its power would naturally be enough to make even Tribulation Crossing Immortal Venerables change color.
But the Nine Heavens Blazing Thunder Formation before them was clearly not at its peak. Otherwise, within a radius of a hundred thousand li, no one below Mahayana Dao Venerable could even approach it.
Li Qingyuan mused inwardly, Even without anyone controlling it, the Nine Heavens Blazing Thunder Formation remained this formidable. It even required more than three Mahayana Dao Venerables to join forces before they could forcibly tear it open.
One could imagine that some heaven-defying object must lie at the formation's core, serving as both its core and source of power, allowing its might to endure to this day.
With this formation's protection, even one or two early Mahayana stage Dao Venerables would have to return with broken feathers.
Li Qingyuan rubbed his chin. "What could the source of the formation be?"
At that moment, heavenly thunder rumbled and lightning roared. The entrance to the palace in the Underground World shook violently, subterranean rivers churned, and the underground world turned upside down.
Boom! Boom! Boom!
Seven Profounds, Heavenly Frost, and Divine Fire, the three Dao Venerables, joined forces. Their radiance blazed brilliantly, forcing the lightning electric light at the formation entrance to flow backward. Their three streams of magic power stirred the Five Elements Great Dao's power and instantly struck a corner of the formation.
The three maintained their output and shouted all together, "Open!"
Boom!
The formation, dense with a lightning