Leviathan didn't run. He simple walked following Raphael and Levina. He made a gun shape with both of his hands.
"BANG!" He shouted repeatedly as countless numbers of rocks pierced through demons like bullets. Some demons hesitated at attacking Leviathan while others just struggled to attack him. In the end it didn't matter he killed and shot at any demon that crossed his path not holding back or showing any sympathy for them.