ASHEN - Black Ashen Feather 06 Location
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The sixth Black Ashen Feather (+2 max health) is found between Whispers and Einarden Reach. You can get to it via the Einarden Reach Ritual Stone, via the Listener's Ridge Ritaul Stone, or via the Whispers Ritual Stone. Since Whisper's is the closer of the 3, this video shows you the path from the Whisper's Ritual Stone.
This video is a part of the ASHEN - Weapon, Armor, Shield & Feather Locations playlist: https://www.youtube.com/playlist?list=PLsxfoGQwyeP42HmRSxCgVw5PASYMMbJxQ