Major Plot Points

Let me explain. . . . No, there is to much; let me sum up.

The Cult of Skyrnyn is a cult of dragon-worshippers, and at least one high-level leader was a cleric of Tiamat, the evil dragon god. They operate around the moon of Jenoa and seem to be fairly ubiquitous. The party has encountered them in various cities and places around the globe.

Their low-level members think that their purpose is to gather money, food, supplies, potable water, even skyship crystals, etc. with the ostensible purpose of purchasing the freedom of several dragons currently dominated by the Knights of the Silver Dragons. Those supplies are sent to a place called the Citadel, which is in the Zyrbryxion Marshes. On the Death Side they also operate as a major players in the slave trade, vacuuming up slaves as much as possible from other buyers, sometimes even killing the competition and taking their slaves. Those slaves are also sent to the Citadel, where the Cult maintains defenses with some of their allies, including drow. (The allies were to include the House of Maramos, but the party's interference led to that vampire coven's extinction.) The Cult also patrols the edges of the Marshes, and are responsible for everybody who ventures into them disappearing. Few even attempt it these days because of the success of their patrols.

The purpose of the supplies is not actually to ransom some of the free dragons. It is to survive the upcoming Dark Times in preparation for something called the Dedication, which will come afterwards.

Other Items of Major Importance:
Voidgate

You also suspect several individuals you have run across are metallic dragons in disguise. However, I'd like you to tell me who you think those are so I can maintain DM neutrality on this issue.

Summaries of Past Codices
Codex I. The party met in the Niktean Wastes and saved an outpost from a goblin attack. The goblins were sent to find a "sacred stick" by some gnomes, the Glittersail Brothers, and their hired guard, Nathan. Nathan was captured and killed, and the party let the gnomes go.

Codex II. The party was sent to kill an ettin, who turned out to be a cursed cleric, Kyrnyn. They successfully helped him return to his natural state and defeated the "evil" portion of his personality.

Codex III. In Hammerdine, the party got involved with a dispute between some merchant guilds, discovered that a church to different gods, the Shrine of Piety, was secretly run by clerics of the God of Death, Nerull. Then they discovered that a vampire had swayed a judge in the city to help cover up nefarious activities. During this Codex, Khaska discovered important records of an ancient folk hero of his people, Tawru. Orensland's father caught up with the elf rogue, and Orensland left the party to avoid a confrontation with the elder elf criminal.

Codex IV. While journeying to Laishtek the party seemed to have been saved by a silver dragon, a very curious incident since all the metallic dragons are supposed to be dead! In Laishtek, they discovered a cell of the Cult of Skyrnyn, and broke it up. Unfortunately, several higher ranking cult members escaped on the Adder Invictus, including Amara, who had been a member of their party but betrayed them. Fan joined the party in this Codex, but was unfortunately killed.

Codex V. The party took a skyship to Twilight, a city under siege from Kagu the Cunning, chasing rumors of the sword of Tawru. After killing the goblin warlord they discovered that Tawru's sword, Kvanir, had at some point in its history become cursed, and had been the source of Kagu's newfound aggression. Orensland rejoined the party in this Codex.

Codex VI. Following on a lead from Codex IV, the party posed as bodyguards for Lady Maramos, a vampire sorceress. They successfully (after much being hunted by and killing Cedric Manson) transported her to her home in Darkcrest, where her coven was to meet with the leadership of the Cult of Skyrnyn. An attack by a rival vampire Coven led by Lady Drakh presented an opportunity to strike, and with the party's interference (and some help from the Bringers of Light) the House of Maramos, the House of Lancel, and the leadership of the cult were all wiped out.

Codex VII?? The plan at the moment is to visit a stone giant seer on Mount Elduin before making their way to a known voidgate, probably stopping in Hammerdine for some brief downtime activities. The last remaining of the Glittersail Brothers is now an ally of the party.