The manhwa does not follow exactly the novel but in the novel vikir wants the he** tree to grow so that he can becomes more powerful so maybe it's just that they took only the bit they wanted in the novel and put together it doesn't hold much sense. Tbh the novel is way better, you should read it

The fifth corps will soon reveal himself (it's the headmaster of the academy) and will send all students of colosseo into a special competence called he** tree which is basically a leveling game tower in which vikir gets really really strong and when all of the students finally get out he reveals himself