This article is part of a directory: AC Valhalla: Complete Guide and Walkthrough
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Getting Books of Knowledge in Assassin's Creed Valhalla allows players to obtain or upgrade powerful abilities. As such, it should come as no surprise that these wealth markers are often prioritized by players. One particularly puzzling book to find is located in Caustow Castle, but players can't seem to find a way past the barred door.

Thankfully, getting past Caustow Castle's barred door to get the Book of Knowledge is actually really easy, but doing so is time consuming for a different reason. This area in Assassin's Creed Valhalla can't be accessed unless the player is on or has completed the quest King Killer, as the area needed to bypass the barred door is locked until that point.

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The King Killer quest is part of the Sciropescire quest line, and must be active before the book can be found. In order to start this quest, players will need to complete main story quests in this region. Eventually, the quest should take players to the interior of Caustow Castle, at which point the barred door can be bypassed.

Throwing Axe Fury level 2 Caustow Castle

Assuming players have the quest active, they'll need to enter the door to the left of the barred door. Under normal circumstances, this door is also blocked off, but during and after the quest it can be accessed. The wall connecting this room and the one with the book has some noticeable structural weaknesses, giving players two ways to break through and obtain the Book of Knowledge tucked away on the other side.

The first way players can break down this wall is by heading out back into the hallway and finding an explosive pot. These red tinted pots are found all throughout England, and are often conveniently located next to areas where they can be used to break walls. Carry this pot back into the room and either throw it at the wall or place it down and loose an arrow into it, as this will cause an explosion large enough to break down the barrier. Alternatively, players with the Incendiary Powder Trap ability can blow the wall up without the pot. For those wondering how to get explosive arrows in Assassin's Creed Valhalla, the book is located in Walden in Grantebridgescire and is actually very easy to obtain.

Inside this room players can find the Book of Knowledge for Throwing Axe Fury, most likely the second upgrade as the other one is usually obtained before this point. This upgrade causes enemies struck by Eivor's throwing axe to stagger, leaving them open to further assaults.

Assassin's Creed Valhalla is available now on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X.

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