ACEO - Melusine by OH-Luri

Melusine is half human, half waterdragon (in some regions the non-human half is also a watersnake or fish).
She appeared as a beautiful maiden infront of a poor french nobleman. She promised him wealth and luck when he marries her, under the condition that he is never to see her take a bath (apparently, she turns into her original form while bathing). The nobleman agreed (despite her being of unknown origins) and get everything she promised him, including beautiful children, rising status and a happy life.
Until, one day, he couldn't hold back and took a peek on her bathing. After he saw her true form, she disappeared back into the ocean.

An Aceo is the same size as Magic or Pokemon cards.