Uvalok

Uvalok is a Devourer a special kind of fiend from the Abyss, neither fully Demon or Undead, but a combination of the two “blessed” by Orcus with extra power.

He was sent by his demonic master to corrupt the Duergar city of Drengingvult. By calling in various demons to aid him, he was able to slay many of the city’s inhabitants, then raise the dead to his service. In that way, he slowly conquered the city and began to rule it.

Uvalok was ambitious enough to consider using his undead servants to attack other cities, but the blight of the Desolation of Azmartheon held him at bay.

In the end, he was slain by the Fire Wasps. Although he was part demon, his spirit did not return to the Abyss, so it is assumed he was destroyed for good.