After entering the cave, Ling Feng immediately activated the Invisibility Ring on his nameless finger, which hadn't been used for a long time, and then assimilated his form with the surrounding scenes. Unless someone stronger than Ling Feng could sense the changes in aura, people outside wouldn't be able to detect Ling Feng's presence.
Ordinary people cannot see Ling Feng's form at all.
Ling Feng summoned Little Fei and rode on its back to fly out of the cave.
Ling Yao saw Little Fei leaving the cave and knew Ling Feng must have left too. She couldn't see his form because Ling Feng was using the Invisibility Ring.
And fearing to get too close to the mansion for fear that Ling Feng and his companions would discover them, the Shui Clan scouts only dared to monitor the mansion's perimeter. They saw a giant beetle flying out from the mansion and were initially surprised.
