A fierce ice witch with flowing silver-blue hair and piercing icy crystal eyes, dramatically casting frozen magic spells atop a futuristic neon-lit skyscraper rooftop during a spectacular aurora borealis winter storm, cel-shaded with bold black outlines, dynamic spell-casting composition with floating ice crystal wisps and magical rune streams, deep cosmic navy and bright electric cyan aurora palette with magical winter glow, fierce determined mood, scattered floating glowing frost particles and distant frozen city silhouettes, fantasy cyberpunk magic concept art with soft bokeh of falling snow curtains and distant aurora waves