Craft a whimsical and majestic scene featuring a captivating magic mushroom castle nestled in a fantastical forest glade. Envision towering, iridescent mushrooms with caps as large as houses, their surfaces shimmering with a myriad of colors like an opalescent gem. The castle itself is built atop the tallest mushroom, its spires reaching towards the sky, adorned with intricate, glowing runes that pulse with ethereal energy. Vines of glowing ivy twist around the castle walls, while enchanted fireflies dance in the air, casting a soft, warm glow over the scene. In the background, a radiant rainbow arcs across the sky, adding a touch of enchantment to the mystical landscape. The air is filled with the sweet scent of blooming flowers and the gentle rustle of leaves, creating a sense of magic and wonder.