Spell of Oblivion

Spell of Oblivion (망각의 주술, Mang-gag-ui jusul) is a spell that is used to erase memories of a large number of people at once.

Po Bidau Gustang used this spell to erase the memory of 43rd Floor inhabitants. A Disciple of Workshop has used this spell to protect the knowledge of the Hidden Floor, in case those who have stored data of themselves in the mirror on the Hidden Floor try to reveal anything about it's existance to the outside world, in turn they will forget everything about it's existence.