Chapter 310 - Explanation 

Right now in the danger zone Sam was killing those Goblin soldiers. Well as you can guess, he already killed those Goblin commanders. It took him at least 2 hours to do that because the defenses of those monsters were strong and he also needed to recover his spiritual energy before killing those Goblin commanders. But fortunately he was lucky today because all this time those Goblin commanders and those Goblin soldiers did not advance toward the city. Everyone got angry because of that invisible enemy that was just attacking them. At any cost they wanted to kill that enemy and because of this, those Goblins did not go toward the city.