The Witcher 3 - Child of the Elder Blood, Skjall's Grave, Veni Vidi Vigo, siren, mirror puzzle

To reach Avallac'h's laboratory, you'll need to find a boat at the docks and take the helm. Once you make it out of the harbour, begin heading in a westerly direction. Keep the lighthouse to your left and continue across the ocean until you reach the island indicated by the objective marker. It's a fair old journey, so be patient.

Child of the Elder Blood

The laboratory entrance lies on the north-westerly side of the island. Disembark at the nearby beach and head on into the darkness.

Talk to Yennefer

Ciri and Yennefer await near the back of the chamber. Make you way over and say hello.

Neutralise the golem

The laboratory's entrance is protected by highly complex magic so, while Yennefer attempts to bypass it, you'll need to deal with the golem that attacks from the rear. The creature is identical to the golems that you've fought before - if a little more powerful - so it shouldn't pose any real threat. Take it down and then, with the laboratory doors open, head on through.

Explore Avallac'h's laboratory using your Witcher Senses

Inside the laboratory, start poking around for clues. Yennefer will call your name, so head on over and speak to her. When your investigation resumes, explore the passage leading south-east, then take a right at the end. Next, follow the corridor along as it winds down into the large chamber. Discuss the genealogy tree, then suggest looking over Avallac'h's notes.

When the conversation ends, head north and push through the door at the end of the room. Inside, ask the woman's name then find out what she knows about Ciri. Tell Ciri that the woman might be lying, then try to calm her down.

Meet Ciri outside the laboratory

When the conversation is over, leave the lab and join Ciri and Yennefer back on the beach. Agree to accompany Ciri to Skjall's grave then head on out, completing the current quest.

Skjall's Grave

Meet Ciri in the Hindarsfjall cemetery

Once you reach the graveyard, suggest looking for Skjall's headstone together. When the locals approach, tell them to quieten down. Let Ciri know when you're ready to leave.

Veni Vidi Vigo

Sneak onto the emperor's flagship under cover of darkness

Next, you need to reach the objective marker in the ocean a long way to the east. Consult the world map to orientate yourself, then approach the nearest fast travel sign and skip on over to Gull Point. On arrival, dive into the water and swim north toward the emperor's fleet.

When the mists settle again, wind your way back and forth between the boats, avoiding the lights that cut through the darkness. As soon as you reach the objective marker, look for the anchor on the side of the vessel and interact with it to continue.

Speak with the emperor on deck and, once you've exhausted the dialogue options, say your goodbyes. Fringilla Vigo accompanies you back to port, ending the quest.

Our Witcher 3 walkthrough and guide can help you with the main story, including the Wandering in the Dark and Family Matters missions, and eventually, one of several Witcher 3 endings. There's plenty of side content, too, including Witcher 3 Contracts, White Orchard quests, Velen quests, Novigrad quests and Skellige Isles quests. Elsewhere, learn about the best Witcher 3 builds, the best Witcher 3 mods, how to make money in Witcher 3, find Places of Power locations, and learn how to do Witcher 3 crafting and Witcher 3 Alchemy And when you're done with all those - we can help you through expansions with our Hearts of Stone walkthrough and Blood and Wine walkthrough.

The Sunstone (continued)

Meet Philippa in the elven ruins

With Fringilla rescued, it's time to visit Philippa and the elven ruins. The ruins are only accessible by an entrance to the north of the island, however, so you'll need to travel by boat. At the harbour, board the nearest vessel and begin sailing north, passing between the rocks and beneath the bridge. Next, travel clockwise around the island, keeping it close on your right. When you see the cave to your right, disembark. Finally, approach Philippa to open the door.

Explore the elven ruins with Philippa Eilhart

Head into the darkness and proceed along the tunnel, keeping Philippa close by. Continue into the cavern as it opens out and be ready to deal with the enemy ambush.

Kill the siren

Exterminate the monsters

To continue, you'll need to annihilate the siren flying around the roof of the cavern. Unfortunately, you'll have to deal with the constant influx of drowners too - and they won't stop coming until the siren is dead. Your best tactic is to pick off a couple of drowners and then, before more can spawn, turn your attention to the siren above.

Launch a volley of crossbow bolts at the creature until it crashes down to earth. It's an easy target while on the ground, so finish it off quickly then wipe out the remaining drowners in the area.

Explore the elven ruins with Philippa Eilhart

Before leaving the cavern, consider visiting the Place of Power to the west. It will temporarily boost your Igni Sign and grant you an additional ability point too. When you're ready to continue, follow Philippa up the steps to the south and wait for her to fix the bridge.

Cross over into the next chamber and follow Philippa through the archway to the right. Head up the steps and immediately deal with the golem that attacks. By now, you should have no trouble bringing it down. When the coast is clear, continue south and climb the stone staircase on the right. Push on a little further then take a left. At the top of the steps, you'll reach another sealed door. Approach Philippa to continue.

When payment has been made, head into the next room and work your way through the dialogue options. Finally, pass through the archway to the east and enter the cavern.

How to solve the mirror puzzle

Set up the mirror system properly

You've a good old-fashioned light/mirror puzzle to solve next. Head in a south-easterly direction and stop once you reach the platform in the centre of the cavern. The mirrors lie at the top of three broken staircases - so you'll need to find an alternative path if you're going to reach them.

Begin by facing the mirror to your right then examine the cavern wall to the right again. A little way on, you'll find a tunnel entrance. Climb on in then take a left. Deal with the sparkly ghost at the top of the steps then pilfer the chest nearby for some decent loot.

Interact with the mirror, then retrace your steps. This time however, don't drop through the hole to the right - instead, continue forward. Follow the path around, climb the ramp then pull yourself up onto the ledge. This takes you to mirror number two. Interact with it to continue.

Next, return to the central platform and approach the final mirror to the east. Climb the steps, hoist yourself up the ledge, then take care of the angry ghost nearby. Interact with the mirror mechanism to align the light and progress the quest.

Examine the Sunstone

That completes the puzzle element of the challenge, so drop back down to the cavern floor and head right. Locate Philippa (look for the illuminated area at the top of the steps), then make your way over. Speak with the sorceress and work through the conversation to end the quest.

Battle Preparations (continued)

Let Avallac'h know everything's ready

Now that you've found the Sunstone, backtrack through the ruins until you reach the beach. If you don't want to rush off just yet, however, there's plenty of treasure (including weapons and armour) to be found underground. Feel free to explore the area before you leave. Note that you'll run into more creatures as you investigate the ruins, so be prepared to fight.

When you're finally ready to depart, use the fast travel sign on the beach and return to Kaer Trolde Harbour. Spend some time preparing for the final leg of your adventure - repairing or upgrading your arsenal, stocking up on supplies and so on - then speak with Avallac'h on the boat. Work through the dialogue options and, assuming you're ready, agree to leave for Undvik.

When you reach your destination, speak with Avallac'h again and go through the plan of action. Next, you're given one last chance to pause the quest and prepare for the final battle. If you're ready to continue immediately, however, let Avallac'h know.

- Keep reading for our guide to finishing On Thin Ice, the final quest in the game.

- Stuck somewhere else? Head back to the first page for the rest of our Witcher 3 walkthrough.