Act as a seasoned fantasy artist with 10+ years of experience in creating ethereal and mystical characters. Craft a highly detailed Midjourney portrait of a [wise ancient sorcerer] standing atop a [floating celestial platform], gripping a [staff embedded with swirling constellations]. The sorcerer's robes should be adorned with [glowing arcane runes], and their eyes should shimmer with cosmic energy. The background should feature a [starry nebula] with distant galaxies, evoking a sense of infinite power. Use a color palette of deep purples, blues, and golds to enhance the magical aura. Ensure the composition is dynamic, with the sorcerer's pose conveying both wisdom and commanding presence. Add subtle particle effects like drifting stardust to emphasize the otherworldly theme.