Weird World: I Can Become Stronger by Killing Weirdos

"This is a big-headed trick, with a very heavy head, so he moves slowly. It is a gentle trick that will not actively harm people. But if you anger him, he will tell you what it means to explode on the spot." In the classroom, Xu Tian pointed at a monster with a huge head and was giving a lecture. Then he pointed at a monster with a green face and a fierce look and said, "This is Yaksha. Don't talk nonsense when you meet him, just go for it." "Just like this!" After saying that, Xu Tian took out a silver revolver from his waist and shot Yaksha in the head with one shot. —————————————— The rules are broken and weirdness appears. How will mankind face this strange and surging wave?