The hunt for Ciri continues with Keira Metz as you delve into elven ruins together looking for her.
Not long after entering the ruins, you will encounter members of the Wild Hunt. In an effort to catch up to them Keira creates a portal, but entering it is optional. If you enter the portal you will be separated from Keira and have to find her. Otherwise, simply ignore the portal until you get the objective to reunite with her.
Assuming you chose to enter the portal, you will now have to defeat the drowners around you. When the path splits both directions will lead to the main chamber, but going to the left has slightly less fighting involved.
When you get back to the area you were in before entering the portal, take a right and then another right to find Keira. You can also just follow her voice as she is screaming for help. When you get to her you will find her fending off rats, whos nests you should destroy with the Igni sign or bombs.
After the dialogue with Keira, follow the marker on the map to continue your search and a dialogue will commence. Afterwards enter the next room and go to the right to find a painting of a swallow. If you have troubles with the toxic gas in the room, you can use the Aard sign to disperse it. Follow the tunnel past the painting and another projection will appear with clues. Do not touch the two symbols nearby of a dog and a kayran as they are both dangerous. Instead, dive into the pool below to find the correct symbol. At the end of the passageway to exit the pool you will see a horse symbol which you must activate in order to proceed with the quest.
Rejoin Keira and follow her into the next chamber. After she creates the portal, make sure you are ready for combat before entering as you will have to fight a golem. Golems move slowly, so you should have ample time to roll out of the way before they strike. Keira will regularly stun the golem, giving you time to heal and recuperate during the fight.
Once the golem has been vanquished continue down the path until you can take a left to finally get to the other side of the bridge from the beginning of the quest. Continue along and you will soon encounter the Wild Hunt once again.
During this part of the quest you will have to stay close to Keira, as the frost from the portals does high damage and will kill you quickly. While staying near her dispatch any Wild Hunt hounds that get close. After the portals are closed, Keira will open a passage to the next room where a boss fight awaits. If needed, be sure to meditate and have potions ready before proceeding.
While fighting Nithral it is best to use fast attacks instead of strong attacks so that you have ample time to roll away when he swings. He takes his sweet time when he’s preparing to attack, so you should have plenty of time. I wouldn’t advise using Axii here, as Keira will frequently attack him and interrupt your stun. Instead, use Quen to shield yourself or Igni to deal some extra damage. When he loses a quarter of his health he will begin summoning hounds to fight for him while he heals. Kill them as quickly as possible to avoid him healing too much.
With Nithral defeated, you can now search the chamber for clues related to Ciri, and find another projection. Keira will give you an item to dispel illusions, allowing you to exit the chamber and the dungeon.
Now you will have the choice of either helping Keira find a magic lamp or simply leaving, the choice is up to you. Either way, the quest will end after the conversation.