Calcification Essence Farming:
Strategy is best for builds that have good single target/cleave damage and can take a few hits. Corrupting Blood Immunity and Chaos Resistance is suggested.
Scarabs Used:
- 1x Calcification
- 1x Ascent
- 1x Stability
- 2x Adversaries
Map Choices:
Bazaar (Highest density with good layout, good div cards, my personal choice)
Toxic Sewers (Okay density with great layout for builds like 
Spark)
Marshes (Good density with good layout, if you don't like Bazaar and want something more open)
Lair (Good density with straight layout, boss can be kind of annoying)
Rolling Maps:
Obtain a large selection of either T16 if your build is strong, or down to roughly T8 if your build is weaker. Put them into a map tab and type "Number of Rare" with quotations into the search field and roll maps in a big sweeping circle.
Alt roll for Increased Number of Rare Monsters and no other mods that brick your build.
Can also Alch/Scour roll these if your build is very strong and you don't care to alt roll, this gives you slightly more map effect but can be MUCH more dangerous
General Strategy:
Bring 3 Stacks of Vaal Orbs with you and choose between two strategies
- Vaal EVERY enemy, this is lower brain usage and generally good.
- Vaal ONLY Purple Essences (Misery, Envy, Dread, Scorn) and Essence Mobs that have 5 or more Essences on them.
Selling Essences with Faustus:
Uptier all essences into Deafening and sell them in minimum stacks of 10 so that you can get the % ratios that will be available. You can also sell them for Divine Orbs if that is available.
Atlas Tree:
Basic Atlas Tree
https://poeplanner.com/a/6gsR - You can drop The Offering nodes if they're too cheap, Betrayal can be swapped to Einhar (it will make the essences more dangerous, just go up the left side instead of right side), Altars can be swapped to either, doesn't really matter.