High Queen Khalida was the Warrior-Queen of Lybaras, a well respected figure across the lands of Nehekhara. She was intelligent, patient, brave, beautiful, and had a strong sense of justice and honour. Her reign was short and it's end stained in blood. Khalida's followers, knowing of the glory she would have brought to the empire, mourned her death greatly.
Her equally beautiful cousin, Queen Neferata of Lahmia, falsely accused Khalida of treason at a banquet with the intention of assassination. Khalida, rising to defend her honour, did not choose a champion to fight for her, accepting the task for herself. Neferata's purpose was to quiet Khalida, who was under the (correct) suspicion that Neferata had studied necromancy and drunk from the Elixir of Damnation.
Khalida attacked with a fearsome might, but she could not hope to defeat Neferata. Her cousin had become a vampire, possessing unholy speed and strength granted by the Elixir. Eventually, to the horror of the guests, Khalida was struck down by Neferata. In the end the vampire, after biting deeply into the throat of Khalida, bit her own tongue and let the blood fall across Khalida so that the two would mingle.
Knowing her fate, that of a vampire, Khalida cried out to the gods to save her. The Asp Goddess, Asaph, heard the cries and appeared to the dying Queen in a vision. The appearance of the goddess cleansed Khalida's body of the vampiric taint and Khalida's last breath was that of a human. Her body was borne back to Lybaras and was buried in the temple of the Asp Goddess in a seated position.
At times, beckoned by the Goddess and under the spell of the great liche Nagash, she rises from her seat and her undead skin slowly regenerates back to its original beauty. She is armed with the Venum Staff and has some ability to cast spells reserved for the Liche Priests. Because of her link to the Asp Goddess, armies with her present contain a unit of archers to honour the Asp goddess. All other archers within the army may be blessed as well, increasing their power.
Sources: Warhammer Armies: Tomb Kings (6th Edition)