Caverna: Het Duel

You may only Excavate a face‑down Room that is accessible via a clear orthogonal path from the Cave Entrance with no Walls or other face‑down Rooms in the way; face‑down Rooms always block. The “Undermining” Action specifically allows Excavation through Walls. (page 5)

Removing a Wall returns it to the supply and grants the depicted Goods, and “Removing the Wall does not affect already‑placed Rooms.” You also may not remove the outer natural Walls. (page 5)

To Furnish you pay the printed cost and place the tile on an empty Cavern that matches the tile’s Wall configuration; dark segments are required, light segments optional, and you may rotate the tile to match. Natural outer Walls count as Walls for placement. (page 6)

Orange Rooms are used when you take an Action tile showing 1, 2, or 3 (the number is how many different orange Rooms you may use), while blue Rooms are always active whenever their trigger occurs and are not used via those numbered Actions. Also, you must always have more orange Rooms than blue Rooms and may not build a blue Room that would make them equal. (pages 6–7)

Yes: the Anytime Action lets you, at any time and any number of times, exchange Emmer, Flax, or Gold for Food at a 1:1 ratio. (page 7)