Alright, the players have captured a spellbook. They don't really know what it is though, they are merely suspicious that they have found a book that's bound in human leather, has pages made out of salamander vellum, and has crude drawings of dicks on every page.
(Note: Secret Page + Extended Nystul's Magical Aura should keep them busy for a while)
Now, eventually they'll figure out the ruse. I was wondering what effects I could put in the spellbook other than the classic Explosive Runes, Sepia Snake Sigil, etc. (I intend to have a second layer of traps behind most pages, the remaining spells are basically stuff to aid in the casting of Planar Binding such as Dismissal, Magic Circle spells, Dimensional Anchor, etc.) Also, the leather is literally the spellcaster's own skin, so scrying on the book should be pretty easy. (The spellbook wasn't very valuable, but it's the principle. It's his book, he wants it back.)