Envision a towering fortress crafted entirely of gleaming black obsidian, its sharp spires piercing the stormy sky. The structure is adorned with intricate carvings of ancient runes, reflecting an aura of mystique and power. Surrounding the fortress is a desolate landscape of jagged rocks and swirling mist, while flashes of distant lightning illuminate the scene, adding a dramatic flair to this breathtaking stronghold of dark elegance.