The greeting card should feature a lively, hand-drawn illustration capturing the fantastical clash between Articuno and Umbreon at a birthday party, with a nod to classic artistic styles like those of Norman Rockwell and Quentin Blake.

**Foreground Elements:**

- **Articuno:** Positioned on the left side, mid-flight, its majestic wings outstretched, their azure feathers shimmering with hints of cerulean and teal. Ice crystals scatter from its wings, with one sharp icicle aimed at the unsuspecting Umbreon.

- **Umbreon:** Positioned on the right, its sleek, dark coat glossy black with vibrant golden rings glowing in defiance. It stands defensively on a pastel-colored party table, surrounded by toppled party hats and scattered confetti.

- **Birthday Cake:** Centered on the table between the two Pokémon, a towering, whimsically detailed cake adorned with rainbow-colored frosting. A small, handwritten "Brother" is cleverly integrated into the icing on the middle tier, nestled among decorative frosting swirls.

**Background Elements:**

- **Party Banner:** Stretching across the top of the scene, this banner is a patchwork of vivid colors—emerald green, sunshine yellow, and bright orange. The banner swings slightly, caught in the breeze created by Articuno’s wings.

- **Sky:** A dusk setting with a gradient of deep violet transitioning to a soft, blush pink, speckled with tiny white stars beginning to twinkle. Articuno's icy breath leaves frosty patterns against this celestial backdrop.

- **Party Setting:** The setting is a lush, whimsical garden with oversized daisies and marigolds, drawn in the delicate, ornate style reminiscent of Aubrey Beardsley. Gentle tufts of grass sprout playfully around the table legs, with fallen petals adding splashes of color to the green ground.

- **Decorative Elements:** Incorporate a mix of art nouveau swirls and art deco patterns subtly in the background, framing the main scene, perhaps etched into the borders of the card, giving it a sense of timeless, enchanting artistry.

Each element should harmonize with intricate, expressive lines and a palette that balances both bold and pastel tones, creating an overall vivid and enchanting birthday scene.

Generated with these themes: Articuno attacking umbreon at a birthday party.

Made with ❤️ by AI.