This was because the attacks unleashed by the five Ancient Treasures used in the Five Elements Ancient Treasure Formation still relied primarily on the destructive force of spell divine abilities!
The searing flames of the fire element and the freezing cold of the water element could weaken the defenses of the formation runes on the Heavenly Secret Beast's armor...
The earth element could suppress the Heavenly Secret Beast's movement speed, while the wood element could penetrate the gaps in its joints and immobilize it...
Finally, the demon-breaking divine thunder penetrated directly into the Heavenly Secret Beast, destroying the mechanisms at its core from within. This was the easiest way to finish off a Heavenly Secret Beast.
Of course, all of this depended on the spell attacks being powerful enough.
If the spells were too weak, they would merely tickle the Heavenly Secret Beast and accomplish nothing.
If Ye Han did not use the Five Elements Ancient Treasure Formation and attacked only with the demon-breaking divine thunder released by the Heavenly Thunder Drum, it might not be enough to destroy the Heavenly Secret Beast's core.
That would simply waste his spell power...
Of all Ye Han's current spell divine abilities, the Five Elements Ancient Treasure Formation was his most powerful spell attack.
However, the Five Elements Ancient Treasure Formation had a drawback: it took too long to unleash. He had to prepare in advance, infusing spell power and setting up the formation...
Although his rising cultivation and spell power had considerably shortened that process, setting up the formation still took quite a while.
Even with Ye Han sending the two Metal Puppets and the Binglian Puppet ahead to clear the way and discover the Ox-Headed Heavenly Secret Beast early, he still would not have had time to unleash the Five Elements