The Joy of Hex
The book named "The Joy of Hex" can be obtained in the book catalog in the drawer labeled "PQR". You can find the book catalog in the library on Phatt Island.
The way you use it:
You need to give the book to the Voodoo Lady in the Swamp on Scabb Island. When she forgets the recipe for the "ash-2-life" potion. You go to Phatt Island and go to the drawer in the book catalog labeled "PQR" find the book and return with it to the Voodoo Lady.