Mutagen slots (5 variations) at The Witcher 2 Nexus - mods and ...
Which abilities in The Witcher 2 contain Mutagen slots? Does the level of points invested in the ability affect the availability of mutagen slots?
Mutagens | The Witcher 3 Wiki
For The Witcher 3: Wild Hunt on the PlayStation 4, a GameFAQs message board topic titled "Best use for red mutagen?".
Character Abilities - The Witcher 3 Guide
For The Witcher 3: Wild Hunt on the PlayStation 4, a GameFAQs message board topic titled "Unlocked the 4 extra ability slots".