Yrrga contacted Ghalwin Forrester in Curse Of Strahd, fashioning herself as a mysterious but helpful masked entity. Understanding that he did not seek personal power for his own sake, she offered him protection in times of need, as he looked to defend his friends. She eventually convinced the young paladin to form a pact with her, granting him minute access to powers typically beyond access to mortals. She also revealed to Ghalwin that his enemy, Strahd von Zarovich, tapped into the abilities of another Dark Power, Vampyr. Requesting further information into the land, Ghalwin formed a warlock pact with Yrrga, granting him Truesight and the ability to access glimpses of her limitless vision.
Though he did not know it, Yrrga gained more control over Ghalwin when he accessed her power, and eventually began to influence his mood. She often attempted to flare his natural smites with radiance, causing blindness both to enemies and allies. Yrrga, like all Dark Powers, required a host to feed on Barovian souls, and she could only consume those who died sightless.
After weeks of sending Ghalwin her limited power, Yrrga attempted to steer him to the Amber Temple by force, and eventually revealed her true appearance to him as he resisted her control. His repeated rejections of her took a toll on the paladin's body, as necrotic damage surged through him. Eventually, in a moment of desperation after fleeing Baba Lysaga in Berez, Ghalwin rejected Yrrga outright using the powers of the Ladies Three. The Dark Power ripped his sight from him as she was abjured, but was never able to contact him again.