Soon after fighting Eysa, the daughter of Surtr, you will start the Cold Embers quest, which will send you to the Vault in question.
The Sol-ok-Mani Vault Book Of Knowledge will upgrade the Explosive Retreat ability, provided that you have already learned it from the Hreidmar Palace Book Of Knowledge. If not, you will learn it now.
Either way, the Wealth collectible can prove tricky to obtain, so check the guide below if you need help.
AC Valhalla Sol-ok-Mani Vault Book Of Knowledge Wealth Location – Where To Find
Let us start with the location of the Sol-ok-Mani Vault, which I pinpointed on the map below.
As you can see, the Vault is located northeast of the Jordeygr Shelter or southeast of Tjarnar Mylna.
After you arrive at the said location, you should find a big entrance followed by stairs. Check the next image to know exactly what you are looking for.
Now go down the stairs to find a light beam puzzle that I will help you solve.
Dawn Of Ragnarok Sol-ok-Mani Vault Puzzle – How To Complete
After you get all the way down, you will find two pedestals on the north side, one emitting a light beam and one that apparently doesn’t work.
You need the one in the lava to be in working condition, just like in the following screenshot.
Behind the pedestals, you will find an inscription that gives you a clue about what to do.
Interacting with the inscription will show you the following message:
One door opens when Sol blazes her path across the sky, the other when her pale brother peeks out from the darkness that follows.
To cut things short, I will tell you that Sol is the sun, and her pale brother is the moon.
So one pedestal works in the daytime (required for the Cold Embers main quest), and the other works at night (needed for the Sol-ok-Mani Vault Book Of Knowledge).
If it’s already nighttime, you are good to go. If not, meditate until it gets dark.
Now aim the functional pedestal at the sphere on the far wall in front of it (like in the image below). You will need the Power of Muspelheim to stay in the lava without taking damage.
After that, go to the sphere on the far wall, and you will see that you can rotate it by shooting arrows at the wings around it. After you spin it enough, the door next to it will open.
Enter the newly opened room and use the Power of Muspelheim again to pass through the lava.
You will find a Cosmetic Scheme at the back of the room that also counts as an artifact, and next to it is the Sol-ok-Mani Vault Book Of Knowledge Wealth.
Congratulations! You learned or upgraded the Explosive Retreat ability in the Dawn Of Ragnarok expansion released by Ubisoft.