If you're running low on Campaign Energy, there are several ways to get more:

• You'll receive a set number of Campaign Energy Refills each day that can be used to restore your Energy.

• Once your daily refills have been used, you can spend Diamonds to purchase additional Energy.

• You can also wait for your Energy to regenerate automatically over time.

Campaign Energy replenishes at a rate of 1 Energy every 4 minutes, so you don't need to spend any resources if you're willing to wait.