Act as a fantasy digital artist with 10+ years of experience in mythical creature design. Create a breathtaking Midjourney portrait of a majestic pegasus with [IRIDESCENT] light-infused wings glowing like [AURORA BOREALIS], standing atop a [CLOUD-CAPPED MOUNTAIN] at golden hour. The pegasus should have a sleek, muscular white body with subtle opalescent highlights, a flowing silver mane, and piercing sapphire-blue eyes. The wings should emit prismatic rays of light, casting ethereal reflections on the surrounding mist. Include intricate celestial patterns subtly woven into the wing membranes. Render in ultra-high-definition with a dreamy, cinematic atmosphere blending realism and fantasy art styles. Use a dynamic pose suggesting the moment before takeoff, with one hoof lifted and wings partially unfurled. Background should feature a gradient of twilight hues blending into deep cosmic blues.