The tale begins in the high halls of Asgard, where the thunder-god Thor, protector of both gods and men, found himself in a state of rare and agonizing vulnerability. Not long before, Thor had engaged in a monumental duel with Hrungnir, the strongest of the giants from Jötunheimr. The conflict had been sparked by Hrungnir’s arrogance, having dared to race his horse Gullfaxi against Odin’s Sleipnir and later boasting in the very halls of Valhalla that he would sink Asgard into the sea and slay all the gods except for Freyja and Sif. Thor, returning from the east where he had been hunting trolls, was not amused by the giant’s insolence. A duel was set at Grjótúnagardar, the Border of the Stone-Fields. In that clash of titans, Hrungnir wielded a massive whetstone as his weapon, while Thor brandished Mjölnir. When the two weapons met in mid-air, the force of the impact was so great that the giant's whetstone shattered. While Mjölnir crushed Hrungnir’s skull, a large, jagged fragment of the whetstone flew through the air and struck Thor squarely in the forehead, burying itself deep within his divine bone.
Thor returned to the realm of Midgard, specifically to the burgeoning trade centers along the waters of Lake Mälaren, near the place later known as Birka. Though he had been victorious, the pain was unlike any he had ever endured. The stone was not merely a physical object; it was imbued with the primordial hardness of the earth and the spite of the giants. It throbbed with a dull, rhythmic ache that echoed the hammering of a forge in his mind. Seeking relief, Thor was directed to a woman of great power and mystery named Gróa. She was a völva, a seeress who practiced the ancient and complex art of seiðr. Gróa dwelt in a secluded hall where the smell of dried herbs and the smoke of sacred fires filled the air. She was known to be the wife of Aurvandill the Bold, a brave traveler who had been lost to the frozen wastes of the north for many winters, presumed dead by many, though Gróa never ceased her rituals of searching.
Upon entering Gróa’s presence, Thor, whose brow was bloodied and swollen, sat before the seeress. He was a god, yet in this moment, he was a supplicant. Gróa recognized the gravity of the wound. To remove a piece of Jötunheimr from the head of the Aesir’s champion required more than physical strength; it required the weaving of sound and spirit. Gróa began the ceremony by tracing runes in the air with her staff and preparing a circle of sanctified space. She began to sing the galdrar—incantations of such antiquity that they seemed to vibrate the very foundations of the wooden hall. Her voice rose and fell in a haunting melody, a vocal tapestry intended to soften the stone and coax the earth-bound matter to relinquish its hold on the god’s flesh.
As the hours passed, the magic began to take effect. Thor felt a strange cooling sensation spreading across his brow. The sharp, biting edges of the whetstone fragment seemed to lose their grip. The stone began to shudder and loosen, inching its way toward the surface of his skin. Gróa’s concentration was absolute; her eyes were closed, her mind traversing the boundaries between the physical world and the spiritual realms where the roots of the stone were anchored. The air in the room grew heavy with the scent of ozone and ancient earth. Thor, feeling the relief and sensing the imminent success of the rite, felt a sudden surge of gratitude toward the seeress. He looked at her weary face, marked by the lines of age and the sorrow of her missing husband, and he decided to give her a gift that he believed would bolster her spirit and complete her happiness.
'Gróa,' Thor spoke, his voice rumbling like distant thunder through the haze of the ritual. 'You do a great service for the protector of Midgard. In return, I shall tell you a tale of my recent journey to the frozen north, to the banks of the Elivagar.' Gróa did not stop her chanting, but her ears twitched at the mention of the icy rivers. Thor continued, describing how he had encountered a man named Aurvandill, trapped in the clutches of the frost-giants and facing certain death in the biting winds. Thor told her how he had placed Aurvandill in a basket and carried him across the treacherous waters of the Elivagar on his back. He spoke of the bitter cold, so intense that one of Aurvandill’s toes had frozen solid. To save the man and commemorate his bravery, Thor had broken off the frozen toe and cast it into the heavens, where it now shone as a bright star, known to all as Aurvandillstá.
Thor leaned forward, his eyes bright with the news. 'And know this, Gróa: your husband is alive. He is even now making his way back to these lands. He is safe, he is well, and he shall soon stand within this very hall to embrace you once more.' The effect of these words was instantaneous and catastrophic for the magic. The wall of focus that Gróa had built around her soul collapsed. The joy that flooded her heart was so sudden and so profound that it shattered her concentration like a hammer on glass. The song of the galdrar faltered; the melody broke into a discord of startled gasps. Her mind, once fixed on the molecular vibration of the whetstone, was now filled with visions of Aurvandill’s face and the warmth of his return.