Corrupt Tower appears in the first half of Malebolge within the Abyss of Time. It will summon another Spurious Book to accompany it if left alone on the field.
Corrupt Tower shadows appear in Chapters 1 through 4 of the Void Quest within the Midnight Channel. They are typically encountered in groups with other shadows that occupy the same floor. In battle, they will cast Balzac on other shadows to up their damage or Mazionga to attack if alone. The Corrupt Tower will also summon additional Dependent Basalt shadows if any were defeated during its turn. Upon defeat, they may drop the Platinum Crown material. Selling 6 Platinum Crowns at Daidara will unlock the Furinkazan weapon for Chie Satonaka.
In Golden, they appear in Chapter 1, 3 and 4. It may drop Lepidolite to trade at Shiroku Pub.