Zahhak

Ahriman, the spirit of evil, found in the ambitious son of a desert king exactly the opening he needed. That son was Zohak. Ahriman did not tempt him all at once: little by little, patiently, not through one temptation but through many, he drew Zohak in, until Zohak belonged to him entirely, his creature in every sense that mattered. It was only then that the purpose behind all that patient work became clear. Ahriman persuaded Zohak to kill his own father. Zohak did it. His father dead, he seized the throne, and the ambitious son of a desert king was, from that day, a king himself.

With the throne won, Ahriman changed his method rather than his aim. He installed himself inside Zohak's own castle, taking a place there as the new king's cook, and he stayed close to him in that role from then on. His cooking was genuinely skilled, and that skill was put to a further purpose. Dish by dish, using nothing more than his cooking, Ahriman taught the new king to eat the flesh of animals, a food Zohak had not eaten before his own cook brought it to his table.

Zohak dreamed one night that he was beaten and put in chains by a young prince. Shaken, he summoned his advisers, the Mobeds, and asked them to interpret it. All fell silent. Only Zirek Mobed, wise and honest, spoke plainly: everyone born of woman dies, he told Zohak, and even a rampart of well-worked iron falls in time. Someone would inherit Zohak's throne and overthrow his power; that someone's name would be Feridun. In terror, Zohak ordered a massacre.

Not long after, a smith named Kaveh came before the king demanding justice. Asked to name the man who had wronged him, Kaveh struck his own head with his hands and made his accusation: his sons' brains, every one of them, had been fed to the king's serpents, and he held the king to account for it. Neither gifts nor words could appease him. He left still angry, and his anger spread: he tied his smith's apron to the end of a lance for a banner, gathered a body of partisans, and led them towards Feridun's palace. Feridun took the smith and his banner as a sign, and decided then to take up arms against Zohak. He set out with his club and his little army, his heart full of joy, and as he marched an angel came down from heaven to instruct him.

At the palace, the confrontation was short. Just as Zohak drew his sword, Feridun, also called Thraetona in the older telling, struck him down with his club. An angel then intervened and commanded Feridun not to kill the demon. Instead, he was to bind him firmly and afterwards chain him in a rocky cavern under Mount Demavand. With Zohak beaten, Feridun mounted the throne at last, avenging both Jemshid and his own father.

Not every telling agrees on how Zohak was finally shut away. One account has Feridun bind him and chain him beneath the mountain. Another says Thraetona instead tunnelled deep into a hillside, threw the demon into a dark cave inside it, and sealed the only way out with solid rock. Both versions agree that Zohak was beaten and imprisoned for good under a mountain; they disagree only on the method: chains, or a hillside sealed shut.