Each battle has different energy requirements, ranging from 5 to 20 energy. This energy regenerates by itself over time but you can always get more inside Star Crates, Free Crates, and also by completing all your Daily Goals or hitting a new Player Level up. Alternatively, you can also buy more with gems.

TIP: Star Crates and Free crates contain a lot of extra Energy per day! Don’t forget to claim those so you can go back to Campaign and collect more rewards!

During special events or game modes, you might encounter different types of energies (Event Energies) this follows the same principle however, be sure to check which battle requires what type of energy and use it wisely.