The Essence league and Hardcore Essence league are the current challenge leagues. The leagues started on 2 September 2016[1] along with the release of Atlas of Worlds expansion (version 2.4.0). There are 40 optional challenges, and players are rewarded with Essence-themed microtransactions after finishing 12, 24, and 36 challenges.
In this league, zones contain a pack of frozen monsters which hold an essence, where taking it frees the monsters imbued with its power. Essences can be used to modify with an items with a specified guaranteed affix, some of which are exclusive to essences. Essences can be traded for higher tiers and can even be corrupted for a chance to gain an even stronger essence or destroy it.
At the end of the leagues, all characters and stashes will be moved to Standard league and Hardcore league. Characters that die in the Hardcore Essence league will immediately be moved to the permanent Standard league.