Duan Ling Tian was speaking the truth and not trying to flatter Agu Li. He also knew that Agu Li was not using his doppelganger now. Earlier when Agu Li protected the Adagon Tribe, the World Cleansing Divine Water could sense the subtle energy from Agu Li's law. His true self also came out from behind the spatial barrier after Lei Hong was destroyed and observed Agu Li.
Agu Li was the top World supreme powerhouse in the Primordial World comprehended the law of water, and the World Cleansing Divine Water was naturally very sensitive to the law of water. As such, Duan Ling Tian knew that Agu Li was not using his doppelganger.
As for his assessment of Agu Li's strength, seeing how he was not injured, it meant that he had easily overcome the Fatal Heavenly Tribulation. Even if he was injured, it was not so severe, and he quickly recovered.
