Summer of Dragons
Tiamat, the Dragon Queen, is universally feared across Tymor. The five-headed dragon goddess summoned her children to destroy the Khanate of Tymor in a cataclysm known as the Dragonwinter. Her motives were unknown, but her children are known to be tyrannical, greedy, and cruel. Most theologians have assumed that Tiamat attempted to conquer Tymor simply because her natural draconic avarice was magnified by her immortality.
Legends say that Tiamat was defeated by the Hazirawn, the Black Knight. He faced her in single combat at the Well of Dragons and slew the immortal Dragon Queen before succumbing to his wounds and perishing along with her.
Because of the horrors inflicted on the land in the Dragonwinter, Tiamat-worship is rarely practiced in public. Most dragon-worshipers are treated with scorn in the best of cases, and with lethal violence in the worst. Some dragonborn try to distance themselves from their legacy of destruction by hunting down dragon cults, while others embrace their bloody heritage by terrorizing nonbelievers.
The Cult of the Dragon Queen is the largest known sect of Tiamat-worshipers in Tymor.