Create a dramatic and epic fantasy scene set in a colossal underground cavern

Create a dramatic and epic fantasy scene set in a colossal underground cavern. The cavern's ceiling is illuminated by a soft, eerie light showcasing a massive, menacing dragon with long, wicked wings and a gnarled, ancient body descending from above. Below, in the cavern's sandy terrain, a vast army of soldiers, clad in dark cloaks and armor, stands poised for battle. At the forefront, a powerful, ethereal figure dressed in flowing white robes is elevated above the ground, wielding a luminous staff that emits a bright, magical light. Surrounding him, the soldiers form a protective formation, demonstrating unity against the monstrous foe. The atmosphere is tense, filled with suspense and the impending clash between the forces of light and darkness. The colors should be dark and muted earth tones, with the white light from the staff casting dynamic shadows and highlights.