Energy

Energy is a fundamental statistic in Clicker Heroes 2, used to enable Monster-damaging "clicks". The game shows two values for Energy, the Current Energy and the Total Energy.
 * The Total Energy is the maximum amount of Energy the player is able to contain at once. By default, this is 100.
 * The Current Energy is a number between 0 and and the Total Energy, decreasing by 1 every time the player clicks on a monster, and increasing by 1 every time the Hero automatically attacks a Monster. Current Energy can also be decreased by a variable amount by certain Skills. Attaining Energy quantities that surpass the Total Energy is only possible through the Energy Pillar Clickable. When this occurs, any increase in Energy is ignored.

Energy Regeneration
1 Energy is restored every time the Hero automatically attacks a Monster (also known as an Auto Attack). This process is interrupted when the player (or a Skill) triggers a click. This can be partly worked around by buying the Synchrony node from the Energy Branch of the Skill Tree, allowing Auto Attacks to continue when or while Skills are activated. It's unknown whether this also affects regular clicking.

Upgrading Total Energy
The Total Energy can be upgraded by buying Equipment with the "+25 Total Energy" modifier, and unlocking Energy-increasing nodes in the Skill Tree.