The Vaults of Atal'Utek Guide
Corrosive Codex
The Altar of Corrosion inside the Vaults of Atal'Utek contains the Corrosive Codex, which allows players to trade in their Corrosive Souls for Corrosive Gifts. Corrosive Gifts are passive effects that boost your power in Midnight's open-world content, including Delves.
Unlocking a new Corrosive Gift requires eight Corrosive Souls, and drop guaranteed from the following sources:
Purging the Vaults Weekly Quest - Drops 2
Defeating Nymrissa Wavecaller Lair Boss - Drops 3 on First Weekly Defeat
Defeating the Ancient Foe in the Vaults of Atal'Utek - Drops 1 on First Weekly Defeat
Other sources, such as defeating Rares in the Coiled Isle, can also drop Corrosive Souls, but aren't guaranteed, with very low drop chances (~5%). The guaranteed drop sources for Corrosive Souls can be completed per Level 90 character, meaning six guaranteed Corrosive Souls per character.
Why Should I Do This?
Corrosive Gifts offer a significant power boost to all open-world content, which includes Delves. Not only is having extra power always a nice plus, but after unlocking eight different Corrosive Gifts, you gain the ability to equip two Gifts at once. Having access to two different Corrosive Gifts is a huge power boost when doing open-world content, Bountiful Delves, or taking on the new Delve Nemesis.
Not only that, but unlocking eight different Corrosive Gifts requires 64x Corrosive Souls. On one character, it would take a player 11 weeks' worth of playing to unlock eight Corrosive Gifts, which isn't even the full Corrosive Codex. Of course, this time can be shortened by defeating rares and completing other content that rewards Corrosive Souls, but not being guaranteed leaves you at the mercy of having good RNG.
By earning Corrosive Souls across alts, you are massively saving the amount of time spent grinding this content to unlock more power.
