Monstruo Marino Bioluminiscente Surgiendo de un Portal en Mapa Antiguo

A majestic, bioluminescent leviathan rises from a swirling, uncharted ocean depicted on an ancient, rolled-up parchment map. The map itself appears to be a portal, with ethereal light bleeding from its edges. Crudely drawn coastlines and fantastical islands surround the creature. The style combines the aesthetic of aged cartography with the visual flair of cosmic horror, rendered in a dark, painterly manner with glowing, unnatural highlights.