Rage of Helheim
This ability can be found in a small cave behind a waterfall, located east of Kjotve’s Fortress. You will need to break the ice barrier with a basic attack to reach the Book of Knowledge at the back of the cave.
Throwing Axe Fury
This ability can be found in a small cave at the southwesternmost point of Notfall, a military settlement southeast of Stavanger. You will need to jump over the wooden barricade within the cave to reach the Book of Knowledge beyond it.
Thorn of Slumber
This ability can be found beneath a tower in Gryttirsand, a military encampment south of Stavanger. To gain access to the Book of Knowledge, you will need to break a wooden barrier either within the tower or outside of it.