Drow-dragon

Drow-dragons (or Draa'zekyl) were an offshoot of both the drow and the shadow dragon, more precisely of the zekyl.

Description
They were shadow dragons but at the same time also drow. They had the same abilities as the shadow dragon, which they developed further as they aged, but added to this the ability to change into an individual drow form and back to dragon form. They could stay in either form for an indefinite amount of time.

They had a predisposition for sorcery.

Society
The reproduction of drow-dragons—not the act, but the result—was a mystery. On one hand, the child of a drow-dragon and a drow was stated to be a zekyl. They had a tendency to produce more male half-dragons than female ones, but those were still half-dragons. Nurvureem, Mauzzkyl Jaezred's daughter, was kidnapped in 1241 DR while still in the womb of her mother and only found in 1358 DR. She was already a drow-dragon despite not having undergone any rituals to turn her into one.

History
The drow-dragon was not a race that sprung up on its own. All drow-dragons traced their ancestry back to Clan Jaezred, a clan of shadow dragons who enslaved the drow of the city of Chaulssin in −221 DR but were killed by their own half-dragon offspring and servants in 634 DR. The population of Chaulssin then traveled to the Plane of Shadow to evade the armies of Menzoberranzan bent on killing them for being heretics in 734 DR. After founding their city Chaul'mur'ssin, they came into conflict with Clan Malaug.

During this conflict, House Jaezred, at that time fulfilling the duties of a secret police force dedicated to finding and killing shapeshifting infiltrators, stole from the malaugrym the necessary magic to divide their dragon and drow parts, and the race of the drow-dragon was born.

In 1136 DR, House Jaezred, and with it a few drow-dragons, returned to Toril. In 1372 DR, nine drow-dragons were known to exist on Toril. It is unknown how many of them still lived in Chaul'mur'ssin.

Eight of the aforementioned drow-dragons formed the leadership of the Jaezred Chaulssin. The ninth was the Jaezred Chaulssin's leader Mauzzkyl's daughter Nurvureem.