Act as a seasoned fantasy artist with expertise in arcane symbolism and ancient lore. Create a highly detailed digital painting of a massive, weathered stone door covered in glowing [CELESTIAL RUNES] that pulse with an eerie [ETHEREAL LIGHT]. The door stands at the threshold of a [FORGOTTEN REALM], its surface etched with intricate patterns that seem to shift when stared at too long. Surround the door with misty tendrils of [MYSTICAL ENERGY], and include subtle hints of the unknown world beyond—perhaps a faint glimpse of floating islands or twisted spires. Use a moody color palette of deep blues, purples, and golds to emphasize the door's otherworldly nature. The composition should evoke both awe and trepidation, making the viewer wonder what lies on the other side.