WitchThis is a build for the Patch 3.27 Phrecia League.
PoB
Moba doesn't directly support Phrecia league trees.
Download and use the PoB: https://pobb.in/TEjCJyEMxCq1
Loot Filter
https://www.filterblade.xyz/Profile?name=Llarold&game=Poe1
About the Build
Bog Shaman's main strength at endgame comes from its ability to convert Energy Shield on gear into life, then scaling that into more spell damage by using 
Sacrifice Support and 
Rathpith Globe.
Bog Shaman grants large bonuses to Skill Effect Duration and Area of Effect, which synergize well with 
Blade Vortex.
Cast Blade Vortex when you are at full stacks of 
Unleash Support (3 by default, 4 with the Caster Mastery). Don't cast it early!
At high gear levels, you can drop Sacrifice Support for 
Awakened Increased Area of Effect Support and combine the Runegraft of the Witchmark and Nightblood Ascendancy passive to gain another ~50M DPS.
Leveling
Use 
Ethereal Knives until you complete Act 4 and unlock Unleash Support, then you can switch to Blade Vortex. Be sure to level Blade Vortex in your offhand as soon as you unlock it in Act 1.
Equip 
Herald of Ash, 
Herald of Ice, and 
Herald of Thunder as soon as you can in Act 2, and add 
Herald of Purity in once you are able to reach 
Presage in the passive tree.
