Poison Fang wanted to remove all the toxins in his surroundings. However, when he saw the large amount of toxins in his surroundings, he felt a pang of pain. This was because these toxins were created using his poison attribute source energy. If he were to remove all the toxins now... Then it would mean that he had wasted a large amount of his stamina and poison attribute source energy.
Right now, his stamina recovery was a little slow. If he were to step back, he would very likely allow Lugh to get close to Rag... At that time, Rag would be in a one-on-one situation with Lugh. Even if the poison fog did not have any effect on Lugh, it still had a certain effect. That was, the poison in poison fangs could be detonated, moreover, it could have the effect of a violent explosion. All he needed to do was to mix the poison with a hundred million other things.