The NPC is a way to exchange resources, which every player can use at their Castles. This can be done at the Marketplace and allows players to exchange on resource type into another at a rate of 1:1. This means without any loses. To do that the player has to pay a price between 10 and 40 Credits, depending on the amount of resources exchanged. This option can be used any time and at any castle that has a Marketplace.
1000 Gold can be transformed to 500 Iron and 500 Wood for 10 coins.