Forest of Harvest is unlocked at lvl85.  In this daily game mode you will earn resources to increase your Base Stats from Enhanced Special training.

The game mode itself is pretty simple: You just send your best team to the Forest, in order to defeat Waves of enemies.

Your goal is to achieve the highest wave as possible. The higher the wave that you achieve, the higher the difficulty is, but you also earn more rewards.

You get an extra chance of attacking at VIP14 and also at VIP17. So it's a total of 3 daily attack chances for VIP17 and above.

As mentioned before, these resources will be used to power up your Base Stats from Enhanced Special training: