Learn the truth about the Vineyard sabotage operation.
The Witcher 3: Blood and Wine - The Deus in the Machina
This quest is suitable for Level 42 and above, and is discovered by finding the optional letters found on enemies and NPC corpses throughout the other Wine Wars quests – Vermentino and Coronata. The tougher part is actually finding this quest through that optional stuff – the quest itself is simple.
Head to the map waypoint given to you by the letters. This will lead you to a small house with a locked door. Look just down a hill in front of the house and you’ll find a red door that can be unlocked with keys picked up when you activated this quest. This leads into a basement.
Down in that basement, there’s a single powerful Archspore. Kill it, then use your Witcher senses to investigate the room in detail. You’ll find information on who is behind the sabotage of the two vineyards.
As an optional objective, you can also burn the seedlings stored down here to prevent any more Archspore being bred for some extra experience. With this done, head back to chat to Liam and Matilda, the pair who kicked off the whole Wine Wars saga.
If you’ve held fire on completing any of the Wine Wars quests, all three so far will now pop as complete so long as you’ve solved all the problems for Verentino and Coronata. If you haven’t see those walkthrough pages for information on how to do so.