Recently picked up this new mini-expansion to Carcassonne. These pieces work with any version of the game you want (as far as any of the Carcassonnes I've ever played go), and the tweak is simple. As long as you have your phantom piece in your "stash" of placeable meeples, you can put him down at the same time as another in a second feature of a tile play. For example you might put your phantom in a castle tile just played and, simultaneously, drop a regular meeple as a farmer outside. As soon as the castle is complete, you get your phantom to replay. The phantoms come in a molded translucent plastic to easily differentiate them from the rest of the game, and they really allow some hyped up combos for higher scoring by all players. A very fun little expansion and, for a couple of dollars, definitely something to pick up!