The Castle of the Ashina Kingdom burned in a sea of flames under Eiko's indifferent gaze.
Unlike her Papa, she was someone that wouldn't bat an eye when it came to destroying an entire Kingdom and its people.
She was a Monster, and it was in her nature to be merciless.
However, since she was raised by Lux and Iris, she still had a bit of compassion left in her.
But, at the end of the day, she wasn't as compassionate as her Papa.
After capturing the King, and slaughtering him in front of the Prince Lionell, Eiko proceeded to exterminate his entire bloodline.
Poseidon also bombarded the city with its blazing cannon balls, turning anything they hit into a blazing inferno.
They first started at the castle, then gradually made the fire spread.
The spread of the flames wasn't that fast, because Poseidon deliberately controlled the scope of destruction that it was dealing to the city.