The water from the torrent opus collects in a great cistern carved into the mountain. Though the torrent opus had not been active for centuries, the cistern was full when the House Wenjansk first arrived in the stronghold. This cistern is accessible via the maze of corridors and tunnels that lead down from Falthringor’s great hall. The cistern is always balmy, a feature that surprised the lowlanders once they reactivated the torrent opus. Inexplicably, the heavenly water that the alchemical engine summons is impossibly warm, and some arcane insulator within the cistern is able to sustain that heat.
Small vents throughout Falthringor disperse this warmth across the castle. As such, the cistern provides not just water for the stronghold but also a small but nontrivial buffer against the frigid mountaintop winds.
In the early days after the lowlanders moved into the castle, High Kestrel Mariusz Wenjansk decreed that the cistern would be off-limits to all but him and the Lord Ratchets. In his view, the cistern was too great a strategic asset to risk. Were someone to tamper with the water supply, they would be forced to drain the entire reservoir. It would take weeks to refill, during which time they would have no fresh water, and the castle would quickly cool. It would likely not mean the end of the Falthringor, but it would be an enormous impediment for an already imperiled stronghold.
Beneath the Cistern
Tunnels and passageways that extend deeper into Mt. Endryr are visible beneath the waters of the cistern. Theoretically, someone could swim down into the unexplored chambers deep below Falthringor. It seems inevitable that there are greater mysteries to uncover that may shed light on the final days of the Duscarn.
Alternatively, these passageways would be much easier to explore if the cistern were emptied. There is a central console near the cistern that could be used to deactivate the torrent opus and open up mountainside sluices, draining the cistern entirely. This would allow for safe traversal of the once flooded chambers deep below the fort
GM NOTE: The “passageways beneath the cistern” is your catch-all excuse to add a dungeon crawl to your Falthringor adventures. If you have a crypt/laboratory/dragon lair/et cetera that you want to incorporate into your campaign without the party even leaving Falthringor, have them deal with the cistern. They’ll either have to sneak into the large chamber or convince the High Kestrel to give them access, and then they’ll have to decide whether it’s worth draining all the warm water. Either way, the mysterious fall of Falthringor’s original inhabitants is a perfect hook to help you plop any additional dungeon module you want into the castle’s basement.
