Horned fantasy beast rearing in a stormy cave

A monstrous, horned equine creature with a dark green, muscular physique and a long, flowing mane is rearing up on its hind legs in a rocky, cave-like environment. Its eyes glow red, and its mouth is open, revealing sharp teeth. A human hand is visible on its neck, and a human foot wearing ornate golden armor is in the lower right corner. Rain is falling heavily, creating splashes of water around the creature's hooves. The overall atmosphere is dark, menacing, and epic. The lighting is dramatic, with strong highlights and shadows, emphasizing the creature's power and the stormy weather. The perspective is low-angle, looking up at the imposing creature. The style is realistic fantasy, with a gritty and detailed rendering of the creature and its surroundings.