This page details where to find all Book of Knowledge locations in Vangrinn, Svartalfheim, part of the Dawn of Ragnarok DLC in AC Valhalla.
There are two Books of Knowledge to be found in Vangrinn, which offer the Rage Axe and Split Shot ability.
Rage Axe - Alethorp Book of Knowledge
This Book of Knowledge grants the Rage Axe ability, or an upgrade for it if you’ve already found it. The settlement of Alethorp is located just southeast of the Hodda Shelter in Vangrinn, as shown in the screenshot below.
To access the Book of Knowledge here, you’ll need to complete a light puzzle. The first thing you need to do here is jump through the window in the north of the room, and then direct the light pedestal towards the door to your left, as shown in the gif below. You can then pull out another light pedestal before directing the light onto it.
Next, move the light from the first pedestal above the door to the south, then jump through the window and head through that door so that you can direct a light from the pedestal there above another door to the east. Behind this door you’ll find a reflective ball which you can place on the pedestal in the centre of the room, as shown in the gif below.
After placing the ball on the pedestal in the centre of the room, you can jump back through the window to the north and direct the light towards the pedestal to the east. Finally, go back to the centre of the room and direct the light from the pedestal here above the door to the east, opening the door to the room where the Book of Knowledge can be found, as shown in the gif below.
Split Shot - Hvithus Book of Knowledge
The small settlement of Hvithus is located southwest of Eitri, or just northwest of the Hofgard Altar, as shown in the screenshot below. Here you’ll find a book of knowledge which grants the Split Shot ability, or an upgrade for it if you already have it.
To access this Book of Knowledge you’ll need to complete another light puzzle. For the first part, find the roof where a light pedestal can be found at the northwestern part of the settlement. You should direct this light towards a pedestal below, to your right, as shown in the gif below. Next, head down to the pedestals which are now connected by the light and shoot the left side of the wheel once, thereby turning the light to open the nearby door to the north. You’ll find a cosmetic scheme artifact beyond this door.
The next thing you’ll need to do is look for a window to the east with a Jotnar portal beyond it. You’ll need to use the Power of Jotunheim to use the portal and enter this building, then destroy the internal lock on the door and take the reflective ball outside. Place this ball on the empty pedestal as shown in the gif below.
Next, direct the faint (as yet inactive) light above the door to the east before shooting the wheel twice on the left side, as shown in the gif below. This will direct the now active light above the door and open it to find the Book of Knowledge within.