sorceress and a member of the Chapter of Sorcerers. She was one of the rectors at Aretuza and the author of The Poisoned Source. She was also extremely obsessive about her appearance and things in general. Tissaia was the one who took a young Yennefer of Vengerberg under her wing. It was she who fixed Yennefer's hunchback and cured her of her various afflictions. During the coup on Thanedd Island, it was she who teleported a heavily wounded Geralt and Triss away from the hands of the approaching Redanian army. After the coup on Thanedd Island, Tissaia committed suicide. Together with the other losses, her death spelled the end of the Council, making way for Lodge of Sorceresses.
- De Vries' Extract is a potion that enables a witcher to see things that are hidden, whether they be behind a wall or spirits.
- An in-game book, Sorceresses and Sorcerers, mentions her sad end.
She is mentioned by Geralt as co-author of the compendium Masters of Magic on Curses – Selected Writings, with Margarita Laux-Antille.
- De Vries is a common Dutch surname meaning, essentially, the Freeze.
- 'Vries'' can also mean freeze