Exhaustion

Exhaustion is a negative effect incurred by some skills. It is the energy equivalent of a Deep Wound. It reduces your maximum Energy by 10, and it is cumulative with prior exhaustion. Exhaustion is displayed as grey on your Energy Bar, and dissipates over time at the rate of 1 maximum energy regained every 3 seconds. Be wary when using exhaustion-causing spells, especially when you have less than 10 maximum energy, as exhaustion can bring one to a maximum energy value below zero.

Skills that cause exhaustion
Certain elementalist skills exhaust the caster. With two exceptions, the effect is triggered at the start of casting, so the caster is exhausted even if the spell is canceled or interrupted. However, Chain Lightning and Invoke Lightning each cause exhaustion after the spell has been cast.

Skills that cause or extend exhaustion on the target
The following skills can indirectly cause exhaustion on an opponent:

The following environment effects can directly or indirectly cause exhaustion:
 * Aspect of Exhaustion inflicts exhaustion every 30 seconds.
 * Sheer Exhaustion causes all spells to inflict exhaustion.

Exhaustion prevention
There is one skill that prevents Exhaustion entirely.