Spell of Memory Deletion

Spell of Memory Deletion is a spell to delete memories. This can be applied to a huge number of people at once.

Po Bidau Gustang
When Baam wanted to exit from the Floor of Death, Gustang used a spell to delete the memories of inhabitants to keep the secret from leaking out to the outside of Floor of Death.

Dowon
In order to make people forget about her role in the war during Age of Genesis, the war hero Dowon erased the memories of everyone from the Wall of Peaceful Coexistence (Dohwa) who knew her identity, except for one person, her own younger sister Khane.