Rumor has it there is a circle of giant thrones in the tundra, where the Sconosciutos of Icewind Dale go when they need answers - an oracle of sorts. The place is not easy to find, but a guide in Dougan's Hole named Yselm claims to know where it is.
Result
Returning to Bryn Shander by airship from Revel's End, the party of adventurers hears their prison-liberator and yeti-hunting friends Aelar and Agaric have recently arrived in the large town in the company of a woman from Targos. The Sea Elf and Gnome introduce the group to the wizard Madouc Mac Donnagh of the Kalteswetteruntergrund (see Meanwhile) and information regarding the secretive Cold Weather Underground's evidence and theories on the Everlasting Winter are shared.
The party takes the most interest in three points:
- Auril is very actively involved in the Everlasting Winter - using her personal power to perform a ritual every night before dawn. (Its effects can be seen on clear nights as the "northern lights" aurora).
- The Kalteswetteruntergrund has viewed her doing so via the weather instruments: a Roc shining with moonlight carries her across the sky.
- Auril is usually noted in myth as one of the "Gods of Fury" - but unlike the others, she is forced away from the world most of the time (the seasons excluding Winter - not to mention in the south were Winter does not come at all!) Two of the Gods of Fury: Talos and Umberlee have taken on more personal manifestations in the world over the same period as the Everlasting Winter:
- the storm god Talos most notably through the Cult of Talos' recent rise of Anchorites of Talos.
- There have been tales that the priests of Umberlee, have successfully sent the great sea monster the Sconosciuto in attacks, sometimes assisting the forces of Talos.
Madouc had come to Bryn Shander to find others to join Aelar and Agaric on an urgent expedition. Meeting with prior adventuring companions is taken as an omen, and hearing the party aligned with the Kalteswetteruntergrund's opposition to the Rime of the Frostmaiden, she urges the group to make haste for a site out on the ice west of the town called Jarlsmoot (which means "meeting place of the kings" in Frost Giant language.
The timing is important because Madouc claims the spirits of the Jarls only appear on the night of the full moon, and the 1st of Tarsakh (each month on Toril begins on a full moon) is only a day away! She believes important questions about Auril and the Rime can be learned by consulting with the spirits on the Thrones of Jarlmoot. She herself is unable to go to the site due to some purification ritual she must maintain to use the weather instruments, but she uses a ritual to place a sense of direction to it in the mind of the divination-apt mind of Alyks.
The plan splits the adventurers into two groups:
- This important once-a-month night is said to also be used by Sconosciutos as a rite of passage, so in the event one of them is seeking the place, Madouc, Phantom and Agaric will create a distraction and otherwise mislead them away from the place.
- A second group pulled on swift dogsleds will seek out the wisdom of the spirit Jarls, led by the direction-ritual.
The Challenges
Arriving with the full moon of the 1st of Tarsakh, the ghostly figures loom above the party, conversing with each other while sitting in the enormous thrones, ignoring the tiny people until Zaknalimar uses Tongues to address the largest giant. This one, calling himself the Jarl of Jarls, Reggaryarva - challenges the party to prove they are worthy in a trial of combat and summons three deadly minions: a Frost Salamander, an Ice Elemental Warrior, and a Frost Giant Skeleton. The battle brings the group terrifyingly close to their own end, but victorious only having Alyks Askaria fallen, targeted for her powerful fire magics, but spared from death by the necromancy of Dex, who also - crucially to survival - had tremendously weakened the giant skeleton with Ray of Enfeeblement.
Upon this success, the party is granted entry into the (frost giant-sized) Questing Halls beneath the Great Throne: "Bring the artifact and ye shall have three questions answered." Within the rooms beneath the ice, the party finds six arches with words of a poem above and large bowls below. A room to the side has two more arches with runes at their peaks and a ring with matching golden runes high on the wall. A hallway to the other side is barred by six floating runes forming a wall.
Alyks uses Comprehend Languages and translates:
The runes forming the wall are:
("Ise" - Ice) 
("Fjell" - Mountain)
("Krig" - War) 
("Liv" - Life)
("Vind" - Wind) and 
("Wyrm" - Dragon).
The poem over the arch-bowls reads:
- Snatch a scale from a sleeping wyrm
- Against the blowing wind, stand firm
- The tallest stone sits atop mountain head
- Life's paths lead to being dead
- Blood from battle starts the war
- Snowflakes fall, till blood stains no more
The archways in the side room are reached by placing the key-runes in the top (aided by Sudon using Fly).
- Wyrm disappears after Aelar sneaks into a dragon's cave to steal a scale through one of the arch-portals opened in the side-room and places it in the bowl, which lights with a flame.
- Vind fades when Zaknalimar, trying to read a figure blows across the bowl.
- Fjell vanishes after Aelar climbs to the top of the rocky pinnacle of the upward-gravity-angled passage in the side-chamber arch, placing a pyramid-like stone in the bowl. (Note the dangerous guardians of the peak, giant mountain goats were horribly burned by the Tiefling Alyks Askaria's fire magic, falling as enormous burning meat-boulders through the archway and sideways to pummel several party members - but providing an excellent meal later).
- Liv dissolves after drops of blood from a survivor of the battle among the thrones above are added to the bowl.
- Krig dims as a sawn-off head of one of the goats is placed in the bowl.
- Ise melts away when snow is placed in the bowl.
Through the now-opened passage, a giant-sized chest is found with a key already in the lock. Just before Aelar turns it, Alyks uses her Wand of Secrets to learn while the chest has no trap itself, there is something about the key. The key is removed, and Aelar realizes it does not in fact fit the lock. Using his own lockpicks (and larger tools such as knives, since it is so large), he opens the chest, revealing a pile of battleaxes and a horn. Reaching for the horn, the axes jump to life, attacking the party. Dex uses Mage Hand to grab the horn and run to the exit. With the successful removal of the Horn Relic, the battleaxes cease their attack, falling to the ground, and the Jarl of Jarls offers the party one question to each of the Seer Jarls, the three ghostly queens in the circle of thrones.
Questions and Answers
Question One: How can we end the everlasting winter?
"Only by preventing Auril the Frostmaiden from repeating her ritual may Spring return to these lands."
Question Two: Where does Auril keep the Roc she rides each night?
"Iskra the Coldlight Roc dwells in a lair atop Grimskalle on the mist-shrouded Isle of Solace in the Sea of Moving Ice. Most sailors and creatures of the sea know how to find the island – and how to avoid it, if they can.”
Question Three: Why is Auril preventing the other seasons from coming to Icewind Dale?
"Thousands of years ago powerful and arrogant wizards built cities that flew in the sky. One of these cities fell deep into the Frozenfar and the Frostmaiden preserved it in a tomb of great ice as a prize and treasure for herself. Silent for all those centuries, something suddenly stirred in the ruins and Auril feared her precious keepsake might escape in the melt while she was away in summer's warmth. And so she devotes a great deal of her power each night to prevent the change of the seasons."
Treasure
The Horn Relic is a Horn of Blasting - shaped like a cone with a lion's head at the large end. It can deal thunder damage and deafness.
The large gold key is worth 25gp, but also has a property of creating a doorway - but Alyks' Identify is unclear on how this works or the danger it might pose - the wand insists a trap is somehow involved.
Return
Phantom and Agaric report there was indeed a frost giant contingent headed to Jarlmoot. Madouc was able to lead them astray with illusions of some sort - and into a time-wasting conflict with a stampede created by the barbarian and druid (and an enormous Snowy Owlbear friendly to Agaric) - delaying their arrival.