Around 400 years ago Borgia was an ambitious sorceress from the most southerly of the Breathing Isles. While still young she journeyed across the sea to the White City and there through wit, guile and treachery she raised herself from an unknown foreigner to the first Duchess Velásquez.
A skilled necromancer and glass sorcerer her magics allowed her to live far beyond her allotted years meaning her many heirs could never ascend to the head of the family. Eventually her many grandchildren rebelled against her in a silent coup and the most powerful sorcerers among them sealed her away in a tomb to the south of the White City; her undead form forever trapped within her crypt.
Over the centuries the Velásquez, ever wary of her unliving presence, added to the tomb; building layer upon layer of magical defences to keep Borgia in and intruders out. Nearly four centuries later, unbeknownst to the Velásquez, the College of The Thousand Arts discovered the tomb and began to excavate it.
After numerous disturbances at the dig-site the College hired a group of Adventurers to investigate the tomb. By breaking through the layers of magical wards the adventurers eventually released Borgia from her centuries of imprisonment; all that remained of her physical form being a golden skull with emeralds for eyes.