Energy

Most battles require energy to participate in. The maximum energy you can have at one time is capped according to your commander level (shown next to your avatar). The cap starts at 40 and increases by 5 with every commander level to a max of 160. Energy regenerates by 1 every 5 minutes (12 per hour) or can be earned through in-game tasks and progression packs. It is not consumed until a battle has been completed. 

Energy packs

Energy packs contain 60 energy and are awarded for completing certain in-game tasks or can be purchased from the Shop or Platinum Market. To get the energy from the pack you will need to open it by going to the energy icon in the currency bar, selecting the plus icon, and then "use".  You can also purchase energy packs with platinum from this panel. 

Note: Don't forget to claim your free daily energy pack from the in-game shop. This can be found under the "Your offers" tab.