Lightning Essence

is the last of the 5 available essences in the game. It is used for focuscrafting and alchemy. Harnessing lightning essences can level the player's Energy Harnessing up to 300, the maximum in the game and it costs 25 production points. The crystals have a chance of dropping Essential Mana instead of the essence.

Source
Dropped by monsters and crystals from the following provinces:
 * Sylvanoth
 * Darkquaver Woods
 * Val Elenium
 * Sienna Canyon
 * Field of Fire