Harvesting or Farming is one of the most rudimentary techniques used in online play (also useful on some singleplayer levels). It allows a player to increase their wood suply, by carefully controlling/monitoring the cutting process of the trees in the immediate proximity to their base. It is usually used on levels like "Craters", "Two on Two", "Sessrumnir Palace", and sometimes Face Off - and on way many more.

 

Farming is done when you are taking braves, depending on the size of the tree (eg.: If the tree has three wood piles you'd take 2 braves, if it has 4 wood piles (maximum) you would take 3 braves) and click on the tree while holding down Ctrl and then Ctrl-clicking the ground. Then it is repeated until you have done the same routine 4 times (maximum you can do, so you can farm 4 trees with 8 fast clicks). Farming a tree with 2 pieces of wood is not recommended as it that tree becomes in risk of being totally cut down, if a brave focus that tree accidentally. Note that you don't have to harvest a 4 wood pile tree with 3 braves, you could take 1 or 2 - it lowers the risk and, as long as the tree is not having the maximum ammount, the harvest purpose is being fulfilled.

Another option could be, after Ctrl-clicking the tree, Ctrl-click it to a plan. That way the wood is already at the plan, speeding up the building process and decreasing the risk of cutting a tree down fully. Another way is to just send your braves to a tree near some huts, then your braves automatically divide the wood between the huts or plans that need it. Of course there is no point farming on maps which have vast amounts of trees ("Pressure Point", "Dead Sea") and other maps.