Kayishen

In life, Kayishen was the high priestess of the false Old Ones that took over the Turochlitan Religious pantheon.
The Chaos Gods gifted her with physical and magical powers and a very powerful and captivating voice.
She managed to pull the puppet strings of Turochlitan for a few years and then orchestrated a coup and led her followers to slaughter all the Skinks in Turochlitan, ruling the Kahoun outright for about a year before Slann Lord Merestar caught wind of her coup instantly crushing her in a magical duel before Merestar ordered the destruction of every man, woman, and child in Turochlitan.
Much later, Lord Renliss the vampire was able to return to the ruins of Turochlitan and recall her spirit as an especially powerful banshee, her once captivated voice now twisted into a crude sonic weapon.
Kayishen is loosely bound to Renliss, but she has more free will and autonomy than an ordinary banshee. In undeath, she has managed to reawaken some of her magical ability and is a moderately powerful spell casting, now capable using the Lore of Vampires and controlling hundreds of undead independently.