Generate a realistic, high-detail image of Fenrir, the legendary wolf from Norse mythology. Depict him as a massive, powerful creature with dark, shaggy fur and glowing, menacing eyes. Show his muscular body in a dynamic, fierce pose, with his mouth open in a terrifying snarl, revealing sharp teeth. His maw should be pierced by a sword, with saliva dripping from his mouth. Include a dark, ominous background with elements like broken chains to symbolize his escape, and incorporate Norse mythology themes such as ancient runes or a desolate battlefield. Ensure the image captures the intense power and malevolent nature of Fenrir