It took Ryu a lot of focus just to mold dirt, making it impossible for him to create a tall cover like a wall. Instead, he made something similar to a trench, splitting dirt to the sides was a lot easier than lifting a wall that needed support. It was also a lot safer, because instead of fighting the powerful winds, it was as if the whole landscape acted as a cover.
Ryu's health points and mana pool were dangerously low, but at least he had enough food to restore his energy. Lea, who was tethered to Bardun, had also spent part of her mana healing goblins.