Essence of the End tooltip states that it has a 4s cooldown for proccing a Void Essence.
However, the cooldown only seems to apply to “(chance to) gain Void Essence on hitting Unique/Rare enemy”. There is no cooldown applied for killing a pack of white mobs, allowing one to gain 3 stacks of void essence instantly. It’s unclear whether the cooldown is supposed to apply here (bug with code) or not (bug with tooltip).
Player.log (3.7 MB)