Spoiler alert. When Mun's leg was healed they said they can only do that because he was a counter but she healed the students broken bones anyway. When he tried to summon Sin (supposedly they are 3x stronger than humans and inside their territory which makes it 5x) and then a small kid tackles him? I could be nitpicking but these small details are important. It felt like they were extending it or poor execution of a plot twist.