https://www.dndbeyond.com/monsters/xardorok-sunblight

Xardorok Sunblight leads the Sunblight clan of duergar which, until recently, dwelled in the subterranean depths beneath the Spine of the World. In the guise of Deep Duerra, the duergar god of conquest, the archdevil Asmodeus visited Xardorok and urged him to conquer Icewind Dale, beginning with Ten-Towns.

Dark Obsession. Xardorok is obsessed with chardalyn and can’t stand the thought of anyone else possessing it. He must have all the chardalyn that Icewind Dale has to offer and is using his ample supply to forge a dragon, which he plans to unleash upon Ten-Towns. See the sidebar for more information about chardalyn.

Father of Nine. Xardorok has been married three times and has sired nine children. He killed his first wife, Thizrun, for plotting to assassinate him. His second wife, Yrraska, was killed in a tunnel collapse along with two of their daughters. His third wife, Marral, was killed during a raid against a mind flayer enclave, along with another daughter and three sons. Xardorok killed his eldest son, Ulthoon, son of Thizrun, for plotting to overthrow him. His surviving offspring are two sons given to him by Marral, named Durth and Nildar.

Clad in Chardalyn. Xardorok wears the following nonmagical items fashioned from chardalyn: a nine-spired crown (two intact spires representing his two surviving sons, and seven partially broken-off spires representing his seven dead children), a suit of chain mail, and a spiked gauntlet.