On this page of our Elden Ring guide, you can view the locations of all Ashes of War and Spirit Ashes found in Lake of Rot, a region accessible by traversing the south-eastern part of Ainsel River Main.
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.
Unfortunately, there are no Ashes of War and Spirit Ashes in Lake of Rot.