Kingdom Legacy: Merchants

From BoardGameGeek:

Your kingdom is a hub of trade, attracting merchants from near and far with their intriguing and often bizarre goods. You can't wait to add these rare treasures to your collection – and you're more than happy to trade your own (slightly less exotic) items for them. Just make sure you have enough to offer, or you might have to break out the old chicken-dancing routine to seal the deal. It's worked before. This is an expansion for Kingdom Legacy. It offers 4 rounds of play, and 26 new cards, most of which you need to purchase from the merchants. But beware, each merchant is only available for 1 round, and once they leave, their offers are lost forever. Most of the 4 rounds of this expansion will be spent gathering the resources needed to purchase cards from the merchants. To actually use and develop those cards, you need to play further expansions, such as the built-in expansions of the base game. To play, you need to perform a purge 7 and purge 2 permanent cards.