Falthringor was built many centuries ago. When the refugees from Wenjansków first discovered the mountaintop citadel ten years back, they were perplexed. They did not know of any civilizations in the mountains, let alone a people from a millennium ago that could construct such a massive fortification in such an unwelcoming environment. As they explored the castle, however, they found texts and mysteriously preserved tapestries that explained the origins of the castle.
Long ago, the Duscarn were a human-like race who lived in the mountains beyond the lowlands. They had weak constitutions and short lifespans compared to the humans who lived in the lowlands. Agriculture was challenging in the mountains, but the lowlanders—even then!—were exceedingly territorial. As such, the Duscarn did their best to eke out a meager survival in the harsh peaks.
Though the details from their own records are murky, the Duscarn somehow became masters of alchemy, concocting potent elixirs that greatly enhanced their lifespans, bolstered their crops, and even sharpened their blades. The Duscarn grew powerful and arrogant. They built Falthringor in the mountains to keep out the lowlanders who had become envious of the now healthy and proud people.
Two things happened next, though in what order is not clear. They poisoned the land, tainting the soil in perpetuity, likely the result of some alchemical mishap. They also built the torrent opus, a colossal tower that could summon pristine water from the heavens and deposit an endless bounty in a cistern within the castle. This water allowed the Duscarn to farm the tainted land, and so they prospered despite the calamity.
Many years later, their hubris got the best of them. They became gluttonous, imbibing stranger and more dangerous potions. Little by little, they transformed themselves from the meek species that first conquered the mountains into the violent and distrustful Duscarn Giants of today. They warred amongst themselves and succumbed to infighting, destroying their powerful empire and falling into a perpetual dark age. Incalculable knowledge was lost, destroyed in battle, or forgotten in the depths of Falthringor. Soon, they could no longer comprehend or reproduce the very alchemy that had turned them into the creatures they had become. At some point, they fled Falthringor and dispersed across the lowlands. The castle was abandoned and remained as such for hundreds of years.