Energy

Energy can refer to either the resource to start missions in the Campaign (except for the missions Tank or Elemental Spirit Asylum) or to the Energy Bar below Heroes / Titans in Battles.

Energy for the Campaign Energy.png
The Energy regenerates by 1 each 6 minutes up to the max Energy refill limit determined by the Team Level. Additionally, players can receive 3 times 60 Energy in the Daily Quests(1-hour cooldown). Combined resulting in 420 free Energy per day.

Free Energy can also be gained by leveling up the Team Level or by receiving Gifts, most Gifts can be stored for an unlimited time in the Mail if desired.

Even more Energy can be bought with Emeralds directly, by clicking on the Energy value, or as Bottled Energy in the Town Shop. The cost for the first option increases if used multiple times and reset at the end of the players Game Day.

Comparison of all possible options, sorted by the Energy per Emeralds ratio:

Energy in Battle
The Energy in Battle is used to activate the ultimate/white skill of most Heroes (with some exceptions) and Titans. They gain Energy in Battles by attacking, using skills, taking damage, or killing opponents.

The Energy is the yellow bar displayed under the health bar of the Hero / Titan. If it is fully charged the border ignites and starts "burning" until activated. Activating the ultimate/white skill depletes the bar to 0%.

The energy bar caps at 100% for heroes, titans, and elemental spirits (totems). Elemental spirits receive the same energy as the titans of their element, but cap at 3,000 energy.

* A successful dodge grants the Energy equal to the potentially lost Health

Videos
Videos explaining the mechanic with several examples: