Geralt visits the Passiflora brothel and does his second favorite thing in such an establishment - plays some Gwent with the madam!

Emerge victorious in your game of Gwent and Marquise Serenity will yield the Morvran Voorhis hero card for the Nilfgaardian deck.

Check out the full guide at:
http://www.gamerguides.com/witcher3

Ebook versions of the guides can be purchased on itunes:
https://itunes.apple.com/us/app/gamer-guides/id599410871