Saving Gemini. Planet Amazon, #5

Andrea finds that she is needed once more to fight a mysterious threat from a neighboring galaxy. The aggressive tactics that King Theos uses to expand his empire has been used on the wrong kingdom. Andrea and her allies would leave him to his fate, the problem is that not only do his new enemies plan to conquer his empire; but now that their predatory instincts have awoken, they plan to take the whole of the Gemini galaxy as their own.
This new enemy turns out to be another legend from Earth's past. If Sarnat's people became Earth's elves, Pindost's people became Earth's dwarves, and dragons are real; then who will this new group turn out to be and how can you fight a fairytale?