Create a detailed pencil drawing of the battle between The Mountain (Gregor Clegane) and The Viper (Oberyn Martell) from Game of Thrones. Depict Gregor Clegane in his full armor, wielding a large longsword, and showcasing his massive and intimidating presence. Oberyn Martell should be depicted in his agile and nimble stance, wielding a spear, wearing light armor, and displaying his confident and fierce expression. The overall style should be realistic and detailed, emphasizing the contrast between the brute strength of The Mountain and the agility of The Viper. Format: 4:5.