What is the meaning of colored vials next to some passive skills

I couldn't find this information anywhere or maybe I don't know what I am looking for.

I returned to game after about 2 months and they redesigned the passive skill tree and now some skills have 3 different colored vials (or something like that) next to the name. Can someone explain what these mean?

Solution 1:

Those vials are the Oils from the current league. They're rewarded from completing the Blight tower defense events and are used on Blight Maps, Rings, Amulets, and Blight Unique items. Using three of them on an amulet or a Blight Unique item will cause that item to provide a passive effect from the skill tree without needing to path to it. The passive effect provided is determined by the combination of oils the item is anointed with, which can be determined by looking at the colors of the vials on the skill.

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