Core Q&A Expanded Answer
Nothing is confirmed yet for Immortals of Destiny. Author James Raquepau has not settled on a song for that novel.
He and Toledo are considering a more pop-oriented love duet between Breanna and Eoin. If that song takes shape, it would be associated with Warriors of Destiny. The return to Warriors of Destiny is intentional, even though the question concerns Immortals of Destiny.
The duet, tentatively titled “Across the Ages,” remains an idea with working lyrics but no announced release date. Turn the Wheel is the existing Warriors of Destiny signature song available through the Bards of Destiny music pages; it should not be confused with the proposed duet.