There are more abilities for you to acquire in Assassin’s Creed Valhalla’s The Siege of Paris expansion. They’re scattered all over Francia, and you’ll have to find them to unlock their secrets. You can find a book of knowledge underneath the Diodurum Ruins. It’s also the location of a Hidden One’s lair. This guide details how to get the book of knowledge underneath Diodurum Ruins. You will need the Siege of Paris expansion to access it.
When you arrive at the location, our best advice is to go to the synchronization point at the top of the ruins and use it. Then, once you’re there, or if you’ve already done that upon arriving, all you have to do is perform a Leap of Faith into the water below, and there will be a hidden entrance. That will be your way into the primary part of the ruins and put you on the path to the book of knowledge.
Proceed to the entrance, and dive through it into the hidden chamber. Next, you can follow the path into the ruins, where you’re going to encounter a blocked entrance and a small gap below you. Dive into the hole below, and dive through the water on the right side. There are a handful of items you can loot along the way while in the water.
Eventually, you’ll reach the other side of the blocked entrance, and there is an explosive pot you can grab and throw at the breakable rock wall. Once you’ve destroyed the rock wall, you’ll gain access to the book of knowledge. The ability you’re going to learn from the book is called Golden Flame. It allows Eivor to attach an explosive to a target and have it detonate after a few seconds.