In an attempt to hide their spellbooks many wizards have learned how to hide their spells in other various types of written works.
Benefit: You can encode a spell within any written work, which is then treated as a spellbook. A spell hidden in such a way requires double the page count (which can be reduced to the standard 1 page per spell level through the Efficient Study feat) and requires you to succeed on a Knowledge (arcana) check (DC 15 + spell level).
If you possess the Scribe Scroll feat, you may also encode scrolls within written works. This requires an additional day and a successful Knowledge (arcana) check (DC 20 + spell level) in addition to the normal costs for scribing the scroll.
Special: Any spellcaster may recognize an encoded spell by making an opposed Knowledge (arcana) check against the original Knowledge (arcana) check result of the caster who encoded the spell. A character who successfully encodes a spell can always read his own encoded spells without requiring a roll. If a character has reason to believe that a particular written work contains an encoded spell, he may take 10 on his Knowledge (arcana) checks.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.