What is the resource needed for relocate Frontline fortress?

You will need to spend stone (rocks) to relocate the front line workshop or any honor buildings. The cost will depend on the plot you move it to as with placing any honor building. Also, when you do relocate it it will lose 50% of its durability and you will need to repair it with more stone (rocks). To relocate it tap on the bulding and tap 'View'. Then tap the Relocate button at the bottom.