If the rules for escaping the lost city were the same as when they came, now that song qingxiao had this letter, it was equivalent to having a 'permit' to leave.
However, she still needed to find out the conditions for the other half of the seal to light up. Also, where did the violent wind and waves come from?
Although the lake surrounded half of the underground city, this amount of water was not enough to cause a huge wave. So, where was the huge wave that could send people away?
She forced herself to calm down and slowly organized all the clues she knew in her mind.
Whether it was professor an's group or the group of bow-wielders, they should be very clear about the rules of leaving the lost city. From the conversation between song qingxiao and the bow-wielding man last night, they probably knew that in order to leave this spacetime wall, they needed a huge wave that broke through the dense mist of the two spaces!