Upon your guild reaching level 8 the Mill will be unlocked.
The best way to get Guild Coin, your team will be guarding a stock pile. Other player may find your stock pile while search in the Plunder tab. Every lose will reduce the amount of Guild Coins received at the end of the Order. Orders can be upgraded to give more rewards, up to a maximum of 6 stars.
You will scout for another player's Order and attack their team, if you win you make off with some of it. Stamina recharges every 2 hrs to a max of 10. The defenders teams power will be displayed after completing your Scout.