On this page of our Elden Ring guide, you can view the locations of Ashes of War and Spirit Ashes found in Deeproot Depths, a region accessible after defeating Valiant Gargoyle. To enter Deeproot Depths, you need to locate a coffin (in Great Waterfall Basin) and interact with it.
Ashes of War are special items that allow you to change the active skill of your weapon. Thanks to them, you can exchange your weapon skill for a completely new one. You activate them by pressing the button responsible for using skills. Spirit Ashes, on the other hand, are items that, when activated, summon spirit companions that will help you in combat.
The ash is in the middle of a destroyed building surrounded by a few waterfalls.
Travel to the marked area. The ash is next to a cut tree. However, watch out for nearby archers.