Arthur could tell where the Dragon Priests were because of their connection but also using his Emperor Eye, which was a heavenly eye to track down people.
Valethar was still hurt because of the attack he received. However, he was good enough to fly. He was still in good condition to fight, all thanks to the healing spells Arthur cast, those of the wood element, and the mixture of alchemy ingredients he made, closing the wound and healing it more after each passing second.
Before the battle even started, Arthur had told the Dragon Priests to move toward the northern mountains, as that's where the other dragons were, and that would be the safest place for them.
Arthur sat cross-legged on Valethar's back and pointed out a direction from time to time.
"How can you track them so easily?" Valethar asked.
He knew about the connection Arthur had with his Dragon Priests, but that was limited, but Arthur was tracking them down so quickly that it made Valethar wonder what the trick was.