Suggestion for the dev: The probabilities for the pieces seem pretty unbalanced now. It's not that it's too hard or easy, but there are too many pieces that are essentially non-viable because they only work in combination with other extremely rare pieces.
For example, there are at least three common/uncommon pieces that explicitly work together with Daaaar, who is "very rare." There are other pieces (rat, sheep, dire wolf) that are only viable with Daaar. I have not seen Daaar in the last two hours of playing.
Other examples of statistically nonviable pairings include librarian/author, mecha (tinkerer/soldier/scrap), vampires (succubus/...paladin?), Djinn (Whale/Sheep/Red Dragon?).
You might consider weighting the probability of certain pieces appearing based on the pieces that are on the board. Increasing the likelihood of scrap if you have tinkerer or alchemist, for example, or increasing the likelihood of red dragon based on the number of sheep or weredragons.