Spell Book
A Spell Book can be programmed with a singular phrase.
After being crafted when you Right-Click the Spell Book to open the spell binding UI. Inside of the UI you'll see the words you've learned.
To construct a spell you select the word you want to insert and then you press the "Select" button. Near the bottom center of the UI you can see the resulting spell book and by hovering you can see the words in the order you selected them.
Don't forget to also insert a Type like sphaera, projectilis, sui or sese. Without a type the spell isn't complete and can't be signed.
Once you're happy with the selection of words you press the "Sign and Close" button and insert a name for the spell.
Once a spell book has been signed it can't be redone!
Spell Book