Original prompt: Darth Vader fighting Sauron with lightsabers.
Revised prompt: A tall, ominous figure in a futuristic black armour with a cape, known for his control over a mysterious force, is engaged in a fierce duel with another towering figure clad in menacing dark armor, with a flaming eye atop his helmet. The scene is set amidst the backdrop of an ancient, desolate battlefield. They're combating each other with futuristic energy swords that project a radiant beam of light.
Color changing lightsaber, nice!