There are the 4 memories that can be accessed by using Ashen Mist Heart: you should interact with the dead Giants on the Forest of Fallen Giants and the dead Dragon in Brightstone Cove Tseldora
There is a new memory, added with the dlc from July 22nd Crown of the Sunken King
They can be done in any order, co-op and pvp are not possible within the areas and you have limited access time.
- Memory of the King - Added via DLC, dialogue from Vendrick
- Memory of the Old Iron King - Added via DLC