Insistence

It became evident that facing the demon king would require Rain to show more of his repertoire, prompting him to prepare for the upcoming challenges and be determined to use some cheap tricks as well. 

"Tactic one," Rain said. "Do you know what you should do when a woman is hitting on you? The answer is: if a woman is hitting on you, your immediate reaction should be where's the sniper while checking your six."

The demon king blinked in confusion, and then he felt an unknown force taking over his body, making it insanely heavier for a moment. He was caught in the effects of the jokester's path, and Rain had enough time to approach and punch him in the face with all his might."

The demon king was knocked to the ground, but he got up immediately. His nose and mouth were bleeding, but his face was of complete anger… he could' fathom how Rain dared to use such a cheap trick on him. If he had calmed a bit, he would do what Rain did, but he didn't.