Harbinger Needles drop from Harbingers, which you can optionally fight after killing timeline bosses. When equipped, a Harbinger Needle causes a boss kill above 90 corruption to Last Epoch gold grant three additional stacks of Gaze of Orobyss.
Since four stacks is the maximum, this means every boss kill effectively counts as four boss kills' worth of gaze. Even better, Harbingers frequently...
English
Arabic
French
Spanish
Portuguese
Deutsch
Turkish
Dutch
Italiano
Russian
Portuguese (Brazil)
Greek