The Witcher series has a problem with it's female characters. A disproportionate number of the prominent women in the series are madly in love with Geralt. It's the James Bond problem - they have to try twice as hard to not be defined by their relationship to the stud of a protagonist.
Shani is no exception to this; she's a nurse who has history with Geralt, but still needs to come off as a well rounded individual in spite of this limiting role in the story.
This is why Evan Rachel Wood, best known for her current role in HBO's Westworld, would be a perfect choice for her. Wood has a great talent for infusing characters with humanity and inner strength. As a nurse, Shani is a deeply caring person, but has the internal fortitude to deal with illness and injury - both magical and otherwise.
Self-evidently a man who writes for the Internet, Robert also writes films, plays, teleplays, and short stories when he's not working on a movie set somewhere. He lives somewhere behind the Hollywood sign.