There’s a book of knowledge in Petuaria Ruins, Eurvicscire in Assassin’s Creed Valhalla.
This book of knowledge will grant the ability of Poisonous Powder Trap.
Here’s how you can get the book of knowledge in Petuaria Ruins in AC Valhalla.
Location of book
The book’s exact location is shown in the map below, marked by the book symbol.
It’s the same spot where you find Ulf stealing treasure in the quest Road To Hamartia.
How to get the book
The book is hidden behind a barred door.
To get into the room, grab one of the oil jars first. Head to the weak stone wall on the other side.
You have to slide through the small gap under the wall to reach this area. It’s also where you came from if you’re doing the Hamartia quest.
Jump onto the right ledge to get near to the stone wall and throw the oil jar.
Enter the room and you’ll see the book of knowledge. There’s also poison gas inside.
The book will grant you the ability of Poisonous Powder Trap.
To escape from the room, just destroy the bar on the door.