Creatures: nixie

Here's a short, clean, on-brand description that matches the tone of your Creatures series and works perfectly for Wattpad or a back-cover blurb:

CREATURES: NIXIE
Written by Jaleal Jacobs

A world-famous artist disappears near the sea-and the water begins to take people with her. As bodies vanish and whispers spread, a legend is born beneath the waves. Drawn by blood, memory, and ancient instinct, the Nixie rises, and the ocean remembers what humans tried to forget.

If you want it even shorter, more poetic, or darker, I can tighten it one more time.