In Path of Exile: Blight, you must stop the spread of the deadly Blight by building towers to defend against monsters held in its thrall.
Our September expansion contains the Blight challenge league, three revamped balance archetypes with new skills and support gems, plenty of new items, two old leagues being integrated into the core game, and a focus on giving you more freedom to choose which aspects of Path of Exile’s content you play and when.
Among other treasures, the Blight yields Oils which Sister Cassia can use to anoint your jewellery. Combine two Oils to enchant a Ring with a potent tower modifier. Combine three Oils to enchant your Amulet with any Notable Passive Skill from the Skill Tree. The twelve Oils vary considerably in rarity, with each combination of them granting a different result.
See this link for a spreadsheet of all Oil combinations.