After the disturbance following the (Sounding of the Draakhorn), Remallia Haventree of the Council of Waterdeep becomes concerned it will be used by the Cult of the Dragon to gather Unknown allies or even call out to Tiamat herself.
Lady Dala Silmerhelve of Waterdeep shares that the last known location of the Draakhorn was the Sea of Moving Ice. While its sound provided no clues as to its current location, the trail to find it would begin there.
The one person who could tell us more is a Tiefling wizard called Maccath the Crimson. No one alive knows more about the Draakhorn than her, she was an expert on such things for the group of wizards called the Arcane Brotherhood. But she has not been seen her for years now. She disappeared on an expedition onto the Sea of Moving Ice.
Maccath reported her progress to the Host Tower by way of Sending spells, and her last report spoke of seeing Ice Hunters paddling their sealskin boats toward a huge iceberg, flattened like a plateau across its surface, but ringed by icy peaks. She had intended to follow the Ice Hunters and investigate the iceberg. After that, there have been no further reports.
Attempts to find Maccath using scrying and other magical means have only located her ship, adrift and heavily damaged. Some of the ship's crew were seen dead, but no sign of the tiefling wizard has been found.
I believe she may have found the lair of one of the White Dragons of the Frozenfar, which would no doubt be protected against most scrying magics.
If Maccath is alive, in addition to the lore she can share regarding the Draakhorn, I'm certain the Arcane Brotherhood would be most grateful to get her back.
Remalia takes this into consideration, and tests her own connections in the far north - ultimately supporting an undertaking be launched to find Maccath.
Result
Following the "orders" from the strange Lords Alliance griffon-cavalryman Mon-Kei, the ship (needs a name!) sets off across the snows then the Sea of Moving Ice, to arrive on an iceberg inhabited by fishermen. The group has little trouble finding Maccath and convinces her its time to end her service to Arauthator and the group confronts the Unknown in its lair. This dragon is a pledged ally of the Cult and it is the intent of the group to end its life here. After great attacks launched as fiery spells, the Alagondar glaive, and counterspells to this adept spellcasting dragon, it is brought low - but before being able to make the killing blow, the dragon freezes Sudon and Dex into a pool, teleporting to order "STOP!", with its claws poised above the heads of the wounded-and-immobilized warlock and necromancer.
An agreement is made to allow the dragon to live in trade for one item each from its hoard and safe return to the mainland.
Along with books and scrolls taken from the (stolen books from the Host Tower) library set up by Maccath, there are worthy magics won by the group:
- Phantom gains the Ring of Alagondar, complementing his Alagondar Glaive
- h'Rothgar gains the Forgemaster's Hammer
- For Alyks Askaria, a Tome of Clear Thought
- Sudon gains a Rod of the Pact Keeper, which can be used as the grip of his hexblood weapon
- And finally, for Dex, a necklace made of grave rat skulls - lending Necrotic Resistance (until he gains this himself, whereupon it means successful saves vs. necrotic damage deal zero rather than half damage).
On the return voyage, Sending between h'Rothgar and Dzaan-now-Meltharond arranges a meeting at the Dark Duchess, where Arveiaturace offers the (buried and frozen) nautiloid's engine in exchange for healing the glaucoma degenerating her eyesight.
The Illithid (mind flayer) engine technology can be placed within the rear of the hull, which then requires being sealed off, as it seems to have a crystalline organic component that likes to wander, with unknown intent. These crystals grow like grasping claws from the surrounding walls, stretching toward but not quite touching the five-foot diameter sphere of shiny black metal with small, transparent hexagonal windows. Unlike on the nautiloid, there are no lights or control knobs, only this dark egg in a cruel-looking nest.
The effect of the design renders the ship susceptible to the Suspension (5th level Transmutation) spell, regardless of weight. Additionally, it allows a skilled crew to use the ship's sails to propel the ship at the wind's speed (up to 30% faster in favorable wind, down to 30% of wind speed if direction is unfavorable). Absence of wind would stall the ship, but currents may change at different altitudes.