Wolf's BOSS difficulty ranking: Phantom Butterfly is also known as Butterfly Teacher. Although it is easy for beginners to fall in love at first sight, Mr. Butterfly is really the best knife teacher. The elite in front won't teach you anything, but she likes to adopt repressive education methods and constantly spray students into puppies, which may make some students who are not psychologically strong enough abandon the pit in a rage, but those who persist and graduate will be deeply moved by the teacher's sentence "What a skill, wolf". As my first BOSS who won many battles, the first time I endured the killing, my heart beat wildly as if there was a thrill of electric current passing by, which I had never experienced in the BOSS war.