Fantasy concept art of a powerful witch in a dark, haunted cave, styled as a Halloween costume. The witch has a punk-neon look, with edgy facial features and a rebellious outfit that includes leather, torn fabrics, and spiked accessories. Her magic glows with vibrant neon colors, like electric blue and neon green. The outfit has Halloween-themed details, such as pumpkin accents, a decorative witch hat, and glowing spider-web patterns. The cave features Halloween decorations like glowing jack-o'-lanterns, hanging bats, and cobwebs, adding a festive touch to the spooky atmosphere. The green moonlight casts a supernatural glow over the scene.