The Blue Moon Abyss (ブルームーンアビス Burūmūn'abisu ) is a cave which is under Luna Nova Magical Academy whose entrance only opens on the nights of a blue moon. There resides the spirit of the Olde Witch Woodward, who is said to be able to answer any question about the past, present or future to those who can appease it.
The Blue Moon Abyss is a great subterranean cave the which can only be entered by the entrance underneath the chapel at the base of New Moon Tower. The entrance apparently only can be opened in the nights of blue moon when the light of this illuminates the Shiny Rod. It is composed of several tunnels of blue stone.
After Akko remembers about the night of the blue moon and what happens during said night, she decides to visit the New Moon Tower, which is rumored to have an area accessible only during nights of the blue moon. Akko enters the chapel of the New Moon Tower, where the staircase leading to the abyss is situated at. Sentient statues in the tunnel start asking Akko why did she come, and she runs away in fear and falls into the bottom of the abyss. At the bottom of the abyss, Akko notices Shiny Chariot, and tries to talk to her, only to find out the "Chariot" was just an illusion. When Akko confronts the blue moon spirit about this, the spirit shows itself to Akko. The spirit asks what she wants, and Akko questions if she can ever become like Chariot. The spirit states that it is not happening, yet she can give Akko the bright future, at the cost of all her past memories and friends. Akko, however, isn't willing to forget all her past memories and friends in change for being exactly like Chariot. The spirit commands Akko to leave, telling her that she will never be like Chariot. Akko, accepting the fact that she can't be Chariot but still can be a great witch, revives the second lost word and transforms the Shiny Rod into an axe, and uses it to damage the spirit, who is revealed to be the spirit of Woodward, one of the Nine Olde Witches. After Woodward shows Akko a montage of the upcoming future, Akko passes out on the ground out of exhaustion.