They see me Grinding, they hatin
The last queen of the Vaal was named Atziri, who owned fabulous treasure. She allegedly sacrificed all those who opposed her, as Siosa's translation of the second Golden Page mentions that she "drenches her altars with the blood of those deranged enough to question her vision". She appears to have been the patron of Doryani - a thaumaturgist - similar to Chitus's patronage of Malachai.
It is said that she "wished to see her likeness reflected in the still waters of history." indicating a vain personality. Siosa mentions that Doryani was a man of "divine talent and demented ambition", comparing him to Malachai. He presumably was a Vaal thaumaturgist of sorts, given the comparison to Malachai.
Atziri sought immortality and eternal youth, inspired by the Vaalish noble and serial killer Zerphi. Zerphi lived for 168 years, yet "it is claimed that Zerphi did not possess the body of a 168-year old, rather that, his corpse had the physiognomy of a man twenty years, no more." It is implied that Zerphi had some method of stealing the youth of his victims. Towards reproducing this feat, Atziri sent young men and women to be "processed" by Doryani, in numbers so large that their names filled "page upon page".
It is likely this quest was related to the end of the Vaal civilization.