The Ashes of Vizima

The Ashes of Vizima is the main quest of the Epilogue of The Witcher. With the Grand Master openly proclaiming a new era of super-humans, Vizima is burning and Geralt has to cross the Temple Quarter to reach Jacques de Aldersberg in the Order’s Cloister. He starts with an ally from Act V at his side (Siegfried, Triss or Yaevinn, depending on his choices), meets King Foltest on the way, and gets one last chance to use Dandelion for storage.

Barricades and debris force long detours through cellars, houses and the sewers, where a zeugl blocks the way. Along the route Geralt may run into familiar faces, and depending on his path he may also face Siegfried or Yaevinn, who can be talked down if he stayed neutral. At the Cloister his ally parts ways, two knights guard the key to the Grand Master’s chambers, and the confrontation inside leads straight into the final quest, Frozen Reflections.

Walkthrough

Start in the Temple Quarter with your ally and meet King Foltest; talk to Dandelion if you need your storage one last time.
With the streets blocked, enter the first house and go down to the basement. A crate there holds the basement door key and the Zeugl Vigor formula.
Make your way through the cellars and climb out through a window back onto the streets.
Reach the second house and get the sewer key (from the person in front of the house, by talking or fighting).
In the sewers, fight the zeugl: destroy enough tentacles to make it surface, hit it while it is exposed, and repeat. Loot its venom for a Zeugl’s Vigor potion.
Depending on your path, deal with Siegfried (neutral or Scoia’tael) or Yaevinn (neutral or Order).
At the Order’s Cloister, your ally leaves. Kill the two knights to get the key to the Grand Master’s chambers and enter for the cutscene that leads into Frozen Reflections.

Quest Consequences & Choices

Siegfried: if you are neutral and tell him to leave the civilians alone, you avoid a fight; otherwise you fight him with his knights and mutants.
Yaevinn: if you are neutral and tell him to stop spilling blood, you avoid a fight; otherwise you fight him and his Scoia’tael.
Characters you spared earlier, such as the Reverend or the ghoul Vetala, may turn up in the first house’s basement, and sparing Vincent Meis adds a novice nun with news of Carmen.