Wizard: I Have a Magic Book That Can Eat People

A college student traveled through time and space to the wizard Hermann, and by the way received a golden finger called the "Magic Book". The world is being polluted by unknown evil spirits. There are wizards who are willing to lose themselves and drink the blood of monsters contaminated with evil spirits to gain strength with their fellow practitioners. But Hel unexpectedly discovered that he could use the magic book to devour other wizards and gain their power without being contaminated. The ultimate move that craves cheating talent. Taboos, forbidden moves, obvious blind spots, fouls, extra dimensions and souls that don't exist in this world. It's not in the textbooks, it's not in the family secrets. I want to break the ancient evil curse. Is there a wizard that cannot be swallowed? Never heard of it at all.