After reaching the summit of The Mountain, Kratos and Atreus must return to the Witch’s house to revive the head of Mímir. However, Jörmungandr’s movement has lowered the water level in the cave - leaving no easy way to reach the surface. Here’s how to solve the Witch’s Cave puzzle in God of War, get back into the Witch’s house, and get the locked rune chest along the way.
God of War - How to get into the Witch’s house:
From Týr’s Temple in the Lake of Nine, leave Brok’s shop and turn right down the stairs. Board your boat and sail into the canyon by the statue of Thor in the south west corner of the lake.
As you reach the mooring, leave your boat. Use Atreus’ shock arrows on the World Tree sap obstacle in front of you and turn the crank to use the elevator.
At the top, move off the elevator platform and continue forward. On your right will be another World Tree sap obstacle. Use your shock arrows again, defeat any enemies that appear and walk through the opening you’ve created.
Destroy the sap and get the Muspelheim cypher:
In this area will be a chest which contains part of the Muspelheim cypher. While you’re here, you can break the Nornir chest seal that’s sitting in the hole in the wall parallel to the entrance. Remember where this location is - you’ll return to it later.
Return to the main path and bear right. Jump down the ledge here.
Turn left when you’re down there, stopping briefly to break the second Nornir chest seal that’s on your left as you exit the room.
On your right will be a gap you can’t jump over. Switch to Atreus’ light arrows by pressing Up on the D-Pad, then fire at the crystal on the other side of the gap.
Cross the bridge that’s created and make note of the Nornir chest you pass. There should only be one illuminated rune on the front of it if you’ve broken the first two seals.
Break the final Witch's Cave chest seal:
Once you’re past the chest, grab a Shatter Crystal from the cache on the path and throw it at the World Tree sap on the wall. Then switch back to Atreus’ shock arrows and destroy it.
Climb into the room, clear it of monsters, then grab the treasure chest and break the final Nornir seal. It’s high in the top left of the room. Then nip back and open the Nornir chest.
Return into the room where you found the final seal and lift the gate on your left.
Boost Atreus to the sand bowl:
As you leave the room through the gate, you’ll see a large movable trolley to the right of the room. You’ll need to use this to move Atreus from one side of the room to the other.
Make sure that the trolley isn’t in the way of the breakable boards high on the wall to the right. Throw your axe at them to smash an opening, then boost Atreus through the hole. He’ll then move around to the walkway above you.
Move the trolley so that it’s in front of him and he’ll climb on top. Drag it to the other side and break the boards blocking him and he’ll jump off again.
Next you need to turn your attention to the sand bowl on the pedestal overlooking the water. It’s to the left of the movable trolley and parallel with the gate you opened to get to this side of the room.
Turn to the left of the sand bowl and look toward the ceiling. There should be more breakable boards here that are covering runes. Throw your axe at the boards, then tell Atreus to read them and activate the bowl by pressing Square while looking at him.
The sand bowl platform will lower, and you’ll hear a scraping noise.
Jump across the gap to the sand bowl platform and open the chest on the right.
Completing the Witch's Cave puzzle:
To finish the puzzle, you have to backtrack to the room where you broke the first seal on the Nornir chest, next to the elevator you used to get up from the boat. If you skipped it before, use Atreus’ shock arrows to destroy the World Tree sap now.
Walk straight forward from the entrance to the room and climb up the well shaft here.
This leads back out into the forest and the entrance of the Witch’s house.