Gone but Not Forgotten
Add your Manifested Pages into the Book of the Forgotten.
The energy unleashed by defeating Headless Ones will turn your Spectral Pages into Manifested Pages. One Spectral Page is Manifested for each Headless One defeated.
Add Manifested Pages to the Book of the Forgotten in the Tower Courtyard.
"Your Cryptarchs are certainly strange, but they have many useful resources from before your Golden Age! I'll put the relevant findings into the Book of the Forgotten." —Eido