The Deltora Book of Monsters was a book that the Palace Librarian Josef wrote after he fled the palace in Del. It was meant to be a collection of detailed description of creatures and hazzards found throughout Deltora.
Josef began writing The Deltora Book of Monsters after he fled from the palace in Del. He was inspired after hearing tales of the monstrous sea serpent, Soldeen, who inhabited the Lake of Tears. Over the years before and after the Shadow Lord's invasion, Josef added to the book from conversations he had with travellers, the peddler Steven, and his adoptive son and apprentice, Ranesh.
At some point after he returned to the palace, Josef presented his completed book to king Lief in the hopes that the young king would read it and gain some wisdom. Lief instead skimmed through the pages and looked at Josef's illustrations.
On the night of the full moon meeting, Josef mentioned his book when explaining to Lief that the dragons of Deltora were divided into seven tribes like the people of the land.