Peetz: After farming the Flotsam Nekker cave for mutagens over and over, I finally got a Madness Mutagen. I was beginning to believe that they didn't exist in Patch 1.2!
Now, I guess I'll have to try that mod that allows you to combine mutagens, since I have craploads of other ones. I did notice another thing... after some time, I stopped getting XP for killing Nekkers there - not that you got much anyway. Don't know if it's because my level is too high (Lvl 14), or if you can only get a certain amount of XP from there?
I believe they have levels as well, and relative to your level you get less and less xp from killing them. In my other post where I got stuck in an endless wraith spawn cycle they stopped awarding me xp after I hit lvl 17.