Aurgloroasa

Aurgloroasa (pronounced ore-GLOR-oh-ASS-ah ), also known as Sibilant Shade, was a venerable shadow dragon responsible for the fall of the dwarven city of Thunderholme.

Motivations
Aurgloroasa was obsessed with research into death, undeath, necromancy, and shadow magic. She also considered herself to be the draconic death god Null's most faithful servant and her most ardent wish was to become his consort and thus a demipower in her own right. Towards this goal she aspired to bring a large portion of Faerûn under her sway and create a draconic theocracy in Null's name.

History
Born in the Year of the Black Dawn, 426 DR, to Shhuusshuru, she prowled her mother's domain in the Far Hills for nearly two centuries until establishing her first lair in the southwestern Thunder Peaks in 616 DR. Both elven rangers from Cormanthyr and dwarven scouts from Thunderholme noted her arrival but neither race chose to move against her. She stayed out of things for the following century and was eventually forgotten by all but the most devoted dragon hunters (none of whom ever actually got to engage with her).

In 989 DR, dwarven miners from Thunderholme accidentally expanded their works into her lair, rousing her from her sleep. She dispatched the dwarves and caved in their tunnel to make it appear as an accident. She became interested in Thunderholme's operations and observed the dwarves via divination magic and spies summoned from the Plane of Shadow.

In 1001 DR she began whispering dark promises to the dwarven city's High priest of Dumathoin, Dagan. Over the next 33 years his ambition, madness and obsession with death increased and he named his voice the "Sibilant Shade", a name which pleased Aurgloroasa greatly. He rose to a preeminent position in the city thanks to her whispers, second only to his king, Emerlin III. The old king died just after his only son and heir disappeared on a trade mission to Selgaunt in 1034 DR making Dagan regent of Thunderholme in their stead (note: both the king and the prince's fates were caused by the dragon's agents). Dagan used his new power to build a huge temple to Dumathoin in the heart of the city which took 20 years to complete. The regent held a grand ceremony to open the temple and shocked the city's population by dedicating it to Null instead of Dumathoin, summoning Aurgloroasa, believing her to be Null's avatar. She proceeded to kill all but 30 of the dwarves and then hunted down and killed those over the next few weeks. All those that died then came to serve the dragon in undeath as skeletons.

She was approached by the Sembian sect of the Cult of the Dragon in 1305 DR after she had already decided to undergo the transformation to lichdom and left clues for the cult to follow (although that didn't stop her from extorting a massive sum from the cult before she actually said that she agreed to the process). She then bribed, blackmailed and fooled enough cultists to weaken the magical bonds they would place on her when she was finally made into a dracolich in the Year of Lurking Death (1322 DR) so that she would still be an active player in their plans.

Since her transformation, the Sibilant Shade has kept quite active (which is unusual for her), instigating a three year civil war in Sembia, stealing the archmage Mhzentul's powerful works and his library of arcane lore, raiding shipping and stealing treasure from boats and other dragons. She could have seized all of Westgate but decided against it.

She then enspelled a hapless adventurer called Orytar into persuading other adventurers to try and defeat her, providing him with a Dethek runestone to Thunderholme that he would give to others. The adventurers would come and she would take their equipment and sacrifice them to her god.

During the Rage of Dragons she used her status as a dracolich to avoid going mad and easily put herself in place to take over the Sembian cell of the Cult of the Dragon. Already a dominant influence on the cult, when the rage ended, she had effectively taken over the cell and with Sammaster dead, she established a ruling triumvirate of the entire cult with Daurgothoth and Alagshon Nathaire which quickly began showing signs of strain.