When word of the capital's uprising and Fereydun's triumph reached the Dragon King Zahhak, a fiery rage consumed his inner core. Under the veil of dusk, he rallied a formidable host of ferocious divs and dark warriors, surging toward the royal palace to exact vengeance. The demon forces mounted the roofs and breached the outer courts from hidden paths. Yet inside the city, an unquenchable fire of resistance raged; the populace—having endured a millennium of suffering under Zahhak's demonic reign—united as one body with Fereydun's forces. Young and old alike scaled the walls, raining bricks, stone, arrows, and spears down upon the tyrant's ranks like a dark hail. A great cry echoed from the fire temples: 'Even if a wild beast sat upon the throne, it would be far sweeter than this foul dragon!'
Seeing the entire city turned against him, Zahhak sought a desperate stratagem. Donning heavy iron armor from head to foot so none might divine his identity, he gripped a sixty-cubit lasso and crept stealthily onto the high roofs of the palace. Looking down into the inner hall, he beheld the raven-tressed Shahrnaz sitting beside Fereydun, her lips curved in bitter curses against Zahhak while whispering secrets of power to the new sovereign. Jealousy and fury struck Zahhak's brain like a sudden flame; scorning his crown and forgetting his very life, he leaped from the roof, drawing a razor-sharp, water-tempered dagger thirsty for maiden blood.
As his feet touched the stone floor, Fereydun charged forward like a tempest! Raising the mighty ox-headed mace, Fereydun struck with legendary force upon Zahhak's head, shattering his iron helmet into fragments. As the tyrant fell stunned to the floor, Fereydun raised his weapon to deliver the deathblow, but in that very instant, Sarosh, the blessed divine messenger, descended from the heavens. 'Strike him not!' cried Sarosh. 'His appointed time has not yet come! Bind him fast like a rock and bear him away to the narrow gorges between the mountains!'
Fereydun heeded the divine herald. He fashioned an unbreakable lasso from lion's hide, binding Zahhak's arms and waist so tightly that not even a wild elephant could snap the bonds. Ascending the golden throne, Fereydun abolished the tyrant's evil decrees and commanded the laymen and warriors to return to their rightful duties, restoring divine order and prosperity to the realm. The noblemen and citizens prostrated themselves at his threshold, giving praise to his righteousness.
Then, binding Zahhak upon the back of a lean camel, Fereydun led his captive far from the city toward the high ranges. Guided by Sarosh, he reached the volcanic heights of Mount Damavand. High upon its crags, Fereydun selected a pitch-black cavern of fathomless depth. Driving heavy iron spikes through the tyrant's limbs into the granite walls, Fereydun left Zahhak suspended in eternal torment, his heart's blood dripping onto the cold stone, forever purging the world of his evil.