The Vampiress of the Swamp

Walkthrough
Talking to the Royal huntsman in the Druids' Cave lets you learn about a bruxa haunting the area around Striga's Crypt, namely close to the "ring of stones" there. Several other bruxae accompany her, so Vampire oil might be a good idea. She's set apart by her name, Lilly, and like with other trophy quests, bringing her head to the Royal huntsman will earn you money and experience.