Grünwald, the primary antagonist, is an ice demon or sorcerer dwelling within an icy fortress. He commands the elements of snow and ice, directing monstrous minions such as silver wolves, a giant pike, and a massive ice mammoth. His destructive path devastated the ancestral fishing village of the protagonist Horus, leaving only Horus and his father alive. This act defines Grünwald as a force of annihilation targeting human settlements.

His core motivation is the domination and eradication of humanity, pursued through direct assaults and psychological manipulation. He offers Horus the role of "brother" and subordinate, an offer Horus rejects, leading to violent conflict. Grünwald seeks to corrupt or control individuals to weaken communities from within.

A key element involves his younger sister, Hilda. Grünwald exerts control over her, granting immortality through a magical "Medal of Life" to bind her to his will. He manipulates her into acting as his agent within the human village, exploiting her singing ability to infiltrate and undermine the community. He compels her to summon swarms of rats against the villagers and later forces her, despite her reluctance, to attempt killing Horus.

Beyond his supernatural powers, Grünwald employs strategy. He exploits existing village tensions, manipulating the deputy Drago into becoming a spy and saboteur. Drago frames Horus for an assassination attempt on the village chief, leveraging fear and distrust to isolate the hero, showcasing Grünwald's ability to exploit human division.

In the climactic battle, Grünwald launches a full assault on the village with his silver wolves and the colossal ice mammoth, transforming into or merging with the mammoth form. His defeat results from the combined efforts of Horus wielding the reforged Sword of the Sun, the united villagers defending their home, and the intervention of the stone giant Mogue. Mogue destroys Grünwald's icy fortress and ultimately crushes the ice mammoth, leading to Grünwald's demise.