Secret Page

When cast, a secret page spell alters the actual contents of a page to appear to be something entirely different.

Thus, a map can be changed to become a treatise on burnishing ebony walking sticks; the text of a spell can be altered to show a ledger page or even another form of spell, etc. 

Confuse languages and explosive runes may be cast upon the secret page, but a comprehend languages will not reveal the actual contents of the secret page. The caster is able to reverse the effect of the spell by the mere utterance of a command word, then peruse the actual page, and return it to its secret page form thereafter. The caster can also remove the spell by double repetition of the command word. 

Others noting the dim magic of a page with this spell cloaking its true contents can attempt a dispel magic, but if it fails, the page will be destroyed. 

Short of an alter reality or wish spell, only will-o-wisp or boggart essence will reveal the true nature of the subject of a secret page spell, if that page is not subjected to dispel magic. 

The material component of the spell is powdered herring scales.