A massive ancient stone archway embedded with glowing runic symbols, standing alone in an endless swirling cosmic void at twilight, ethereal nebula clouds drifting through the portal frame, cel-shaded with bold black outlines, dramatic centered composition with swirling cosmic dust particles, deep cosmic purple and bright cyan magenta palette with glowing runic light, mysterious transformative mood, scattered floating star fragments and distant galaxy spirals, ancient magical gateway concept art with soft bokeh of distant cosmic nebula clouds