He's the Key to the World Gate?

 As the Sun-Moon Dragon Spring escaped, the vast underground space suddenly became dark and dead silent. Nothing else existed.

The Dragon Phantom Lord did not waste any of it. It opened its mouth and swallowed all the fog that filled the underground space. The fogs were released by the Sun-Moon Dragon Spring. When condensed, it was equivalent to dozens of drops of ordinary saint spring.

The Dragon Phantom Lord had gained a lot this time. He had swallowed thousands of drops of the saint spring, including nearly hundred drops of saint spring essence. It was enough to restore his strength and help him refine the Son of Darkness effectively.

In this way, he might be able to regain his peak strength soon.

A streak of holy light flashed. An exquisite jade ring appeared in Zhang Ruochen's hand. It was a high-quality Ring of Dimensions that belonged to the Lord of Elixir.