I have the quest but have no idee what to do.. i only have a bottle of strange vine or something and a quest called "a venerable vintage"....

haven't done that one yet, but go to your journal, click on this quest and then, when it stays for it's own in your journal, press the small button called "map" in the right top corner of the journal. Then a red/green marker should occur, which you ought to follow

well.. yeah... i get that.. im lvl 26. . but in this quest there is no marker...

darn Sorry for the dummie-explanation
Sorry for not knowing any remedy for your problem either .

I *think* that is the one about the... Shadow something wine if I remember? Shadow Banish?

okej... thx.......