Winx Club Forever
At first, they could not open it, until the Winx won the challenge in Graynor, and gained the Nature's Boon to unlock the book and open it. The Sirenix Book gave the Winx the Sirenix Boxes and their Harmonix powers. It also gave the Winx Club a warning about the curse that was bestowed upon the power; if the Winx did not complete the Sirenix quest in one lunar cycle, they would lose their powers forever.
During the time, it gave Winx riddles that leaded them to the Gem of Self-Confidence through Andros to Solaria, Gem of Empathy through Melody to Zenith and Gem of Courage through Linphea to Domino. When final gem was acquired, the book disappeared as it was no longer needed.
It has a burgundy cover with silver designs in the corners and a gold moon in the middle.
- In the Italian version, the Book has a male voice, while in English version it has a female voice.
- The Italian VA: Marco Bassetti, English VA: Kari Wahlgren
- The Sirenix Book's appearance is similar to the book that was used to summon an Anthropomorphic Monster, a creature that looks like Professor Avalon in Season 2.