Wine Wars: The Deus in the Machina - Toussaint (Blood and Wine)
This quest will begin once you've found the required items if you haven't completed either Wine Wars: Vermentino or Wine Wars: Coronata yet. Both of the required items to unlock this quest are found while doing the Vermentino and Coronata quests. You must complete this quest before turning in the Vermentino or Coronata quests too, other wise this quest will fail. Completing this quest will unlock the Wine Wars: Consorting Quest.
For help finding both of the items you need to begin this quest, use my screen shots below. Where I am standing in each of these is where you'll find the required evidence.
The first thing you'll need to do for this quest is travel to the southern portion of Toussaint where you will find a cellar (screen shot below). Inside this cellar there will be some Archespore enemies that you need to defeat as well as a Stocktaking Report that you must find and read for a quest update.
Archespore Weaknesses: Cursed Oil, Aard, Igni, Dancing Star (Bomb)
After reading the Stocktaking Report return to Liam and Matilda and speak with them to complete this quest as well as the Wine Wars: Vermentino and Wine Wars: Coronata quests. Instead of being individual quests they'll now merge into the Wine Wars: Consorting quest.