Stallune is a mirage monster.
While generally discounted as a myth, various teenagers and hikers have come forward over the years, insisting on the existence of this mysterious monster.
Said to live on a distant beach, cut off from the rest of the island, Stallune appears under the moonlight on the still sand. Around it, a small magical crescent floats. The ethereal moon will spin and rise according to Stallune's whims. Seeing the crescent rise sharply is a sure indicator that you have been spotted, causing Stallune to flee, and shortly after, vanish. Only a handful of sparkling sand remains where Stallune once stood.
Despite the vivid and fantastical tales, Tamers travelling deep into the wilderness have waited for days on-location, coming back with nothing of value to report.