The circle of flames created by the Elemental Empress prevented anything alive inside the Beast Ranch from escaping. The Kitsun and bloodthirsty beasts were imprisoned in the Beast Ranch alongside Michael, Tiara, and Lilica.
At the same time, the Elemental Empress controlled the circle of flames precisely. She received a flood of energy when Opars used Energy Imprint on her several times. It allowed her to utilize her power to push the flames closer to the Beast Ranch to burn her enemies and push both beasts and Kitsun closer to the center of the Beast Ranch.
This allowed Mika and the other Forest Elves to focus on archery, releasing batches of arrows without the need to aim precisely. After all, there were more than enough bloodthirsty beasts that barged through the iron fences in a desperate attempt to escape the blazing flames.