Grunwald, an ice demon, relentlessly pursues humanity's eradication through manipulation and destruction. His core power allows command over ice and snow, enabling control of minions like silver wolves and a colossal ice mammoth. These forces unleash devastation on human villages. Grunwald's history includes obliterating multiple communities, notably Horus's coastal settlement and Hilda's home. He employs psychological manipulation, exploiting fear and trauma to incite internal conflict among humans, as demonstrated when he corrupts a village into self-destruction. His influence extends to Hilda, whom he manipulates after destroying her village. He binds her as his sister by offering an immortalizing "Medal of Life," enforcing dependence through psychological control, including forced visions of betrayal.

Grunwald attempts to recruit Horus by offering power and status as his brother, framing their alliance as unavoidable. Upon refusal, he escalates attacks, targeting Horus's new village with rat swarms, wolf assaults, and the ice mammoth. His motivations blend genocidal intent against humans with strategic threat recognition, evident when he acknowledges Horus's potential.

The demon's downfall unfolds during the village's final defense. Horus and villagers counter his ice powers with fire, while the reforged Sword of the Sun and the stone giant Mogue dismantle his fortress. Grunwald's defeat ends his reign physically and symbolically, freeing Hilda from his influence.