Kingdom Legacy: Feudal Kingdom - Merchants

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.