Whisper of Atonement is a brand new legendary gem that drops exclusively as a reward for Echoing Nightmare completion. It drops once per completed Echoing Nightmare, and has the following notable features: Its sole purpose is to be used for augmentation of Ancient Legendary items. The legendary gem drops pre-leveled to the tier of the Echoing Nightmare you achieve, up to a maximum of gem level 125. This makes the basic goal of your every Echoing Nightmare to reach at least tier 125, though you will ideally reach the reward cap at tier 150. Note that the Whisper of Atonement's level cap is actually 150, and you can finish its leveling the regular way — by completing (suitably high) Greater Rifts.