Craftsmen are special workers that assist you in constructing or upgrading your Castle's buildings. Each additional Craftsman you hire adds an extra construction or Upgrade slot to your Castle, allowing you to Upgrade or construct multiple buildings simultaneously.
To purchase a Craftsman, place your cursor over the "+" button next to the "Construction" button and click "Purchase Craftsman":
A pop window will appear, showing how many Craftsmen you have at your disposal. To hire additional Craftsman, press the button with a green "+":
Once you have reviewed the price information the pop-up window, click "Purchase" to finalize your decision.
NOTE: The number of Craftsmen you may purchase is limited. Once purchased, they cannot be removed from your Castle.