Energy

Energy is the primary resource used by rogues, druids in Cat Form and Brewmaster and Windwalker monks. Energy regenerates at a fixed rate of 1 energy every decisecond (i.e. every one tenth of a second), in and out of combat, and is under most circumstances capped at 100. This makes energy a very fast-regenerating and fast-depletable resource. Certain energy-using rotations may benefit from energy pooling to maximize efficiency. Many abilities using Energy have a fixed Cooldown#Global cooldown (GCD) of 1.0 seconds that is not affected by haste.

The size of the energy pool and the regeneration rate are both constant - they do not increase with levels, but certain talents and abilities can affect energy regen and maximum energy. In addition, some talents, abilities, items and equipment effects can restore lost energy or allow free usage of abilities that would otherwise require energy. Haste also increases energy regeneration rate, but its effects are negligible unless your character stacks a considerable amount of Haste (regen rate increases by roughly 1 energy per second for every 10% Haste).