Water hag mutagen is an alchemy ingredient and is used to craft Water hag decoctions. They act like lesser red mutagens when placed in the diamond-shaped slots in the character panel.
- In an undocumented change for Patch 1.08, all mutagen icons were changed. However, there was still a bug for those on Steam and Origin that didn't reflect this and was later fixed in Patch 1.22. Despite this, some may still see the original icons instead, even with a fully patched game.
- A guaranteed source is the Contract: Muire D'yaeblen quest in Skellige.