Before either the chromatic or metallic dragons were created by Tiamat and Bahamut, there was an older generation of dragons created by Io. Many of these ancient dragons died in the battles of the Dawn War, and only a small number managed to outlive their creator. When their god was sundered by the primordial Erek-Hus, most of the remaining elder dragons sword themselves to one god or the other and continued to fight against the primordials and their elemental minions.
One elder dragon, Kiraxisanth, refused to bow to either of the new deities and instead claimed they were both usurpers attempting to steal Io’s glory. He withdrew from the Dawn War and embarked on a personal quest to return his creator to life and godhood. After centuries of research and failed attempts, Kiraxisanth began to feel the pull of his twilight and feared that he would fail in his mission and leave Io abandoned. That desperation drove him to commit a blasphemy against his own god and undergo a ritual to become a dracolich.
While the transformation has allowed Kiraxisanth to survive longer than any other dragon, he is ashamed of his choice and feels that his only chance at redemption is succeeding in his quest and restoring Io.
Kiraxisanth is the oldest dragon in the multiverse, centuries older than either Bahamut or Tiamat, and can nearly rival deities in combat. In addition, he has had thousands of years to become a master of arcane magic.
Over the long millenia of his undead existence, Kiraxisanth has persuaded other dragons to abandon the younger draconic gods and turn to Io’s faith. His eight most senior disciples and himself form a council known as the Nine. These nine wyrms come from both metallic and chromatic dragonkind, but they are united by their desire to ensure Io’s return. Most often the dragons that make up the council are scattered throughout the planes working independently, but they meet once each decade to share their knowledge and plot how to bring about their god’s resurrection.
If you’re using the AGE system, then you can use the dragon stats in the Mystara Adversary Compendium I as a baseline for the dragons of the Nine. Those dragon stats, by Byron Molix, were what I used as a starting point for Kiraxisanth as well. The pdf also has some special stunts for dragons that could be added to the dracolich.
For D&D, pick any selection of elder and ancient dragons that you feel like using.
The Order of the Arcane Flame
While Kiraxisanth abandoned the Dawn War, he continues to have a deep hatred for the primordials and other elemental creatures. After witnessing an invasion of efreet and fire archons in the Shining South, he worked with several human and dragonborn sorcerers to create the Order of the Arcane Flame. This group of spellcasters is devoted to studying and combating the powers of the Elemental Chaos.
Only the Order’s inner circle knows of its ties to Kiraxisanth and Io, but the dracolich does occasionally make use of the order’s many members to gather information or search out artifacts that he believes will help him in his quest. Most often the junior members conducting these missions have no idea that they are working towards Io’s eventual resurrection.
The Temple of the Dragonfather
Kiraxisanth’s lair is a massive temple of Io drifting in the Astral Sea. The ancient temple was built to accommodate dragons with hallways 30 ft wide and great rooms large enough for several wyrms to lounge in comfort. While the temple is now abandoned other than the dracolich, it is warded with countless enchantments and traps designed to protect Io’s last sacred site and Kiraxisanth’s hoard of relics and wealth.
EDIT 25 May 2020: Removed some dead links to Dragon Age Oracle.