Empowered Rift Core

Source
Empowered Rift Cores can be created by speaking to Evelune Soulreaver after the Class Hall upgrade Fel Hammer's Wrath has been researched. They take 100 Order Resources and 10 minutes to make and can only be used every 18 hours.

As a quest objective
This item is an objective of Unleashing our Wrath (demon hunter).