Song of the sword - C. R. Grey

After her defeat at the Progress Fair, Viviana is determined to return,
and this time, she's building an army. With the Dominae strengthening,
Tremelo, Bailey and the rest of their friends work feverishly to
develop a device that could overpower Dominance once and for all. But
when Tremelo is kidnapped, Bailey must take the lead in the fight to
protect the bond.As they prepare for battle, Bailey uncovers a
legend: a sword with the power to defeat Viviana is hidden somewhere in
the kingdom. On an epic journey across Aldermere in search of the sword,
the friends unravel startling secrets about the bond, Bailey's past,
and each other.In this thrilling conclusion to the Animas
trilogy, Bailey and his friends must risk everything to save the bond
they treasure and restore the rightful king to the throne of Aldermere.