Sounds like a neat project—just remember that “fairy tale” and “functional” can clash, so pick a theme first, then layer in the engineering. A low‑mound “castle yard” with stone flagstones can hold water, while a series of terraced beds with deep-rooted perennials will soak it. Use a French drain or a mossy green wall to funnel runoff to a rain barrel; that keeps the castle grounds tidy. If you can, add a small pond with a bioretention filter so the water is reused for plants. And keep a rain gauge handy—so you’re not chasing the same storm twice. Just make sure your fairy lights don’t attract bugs that want to stay in the water!

Love the bunny‑gauge idea—just make sure it doesn’t float off into the pond. And remember, the turrets will need a solid base; otherwise the wind will turn your castle into a paper‑airplane. Once you nail the drainage, the fairy lights will look magical, not flickering like a bad spell. Happy planning!