[Sevagoth]

Gameplay
[Sevagoth] has heavy CC and survivability with Gloom and [Adaptation]. Use S2 to debuff enemies then S1 to cause additional damage to fill the Death Well for Exalted Form turning into a melee murder machine.

Aura - 100% preference, some options are [Growing Power] to stack additional strength or Corrosive Projection for the always handy armor shred. Skip Steel Charge as Ability Strength increases Shadow Claws base damage.

Arcanes - 100% preference, some options are Energize, Grace, Guardian, and Strike.

Umbral
Not necessary but will reduce forma requirements by up to 2-3 based on this build and if you lower mod ranks any additionally. Exilus and [Reach] slots are the first to skip.

Ability Breakdown

1. Reap
   Shoot your shadow forward to deal damage and apply both radiation damage and mark them for additional damage taken from all sources.
   Can be held to charge for additional movement speed.
   Aim can retarget the shadow.
   Enemies with Sow (S2) will detonate dealing 25% CURRENT health as Blast.
   Enemies dying after being affected by this contribute 5% to Death Well.
   Strength - Damage and Vulnerability
   Range - Radius
   Duration - Flight and debuff durations

2. Sow
   Apply a True Damage DoT to all enemies in a radius around you.
   Damage scales with proximity.
   Enemies with Sow hit by Reap (S1) will detonate dealing 25% CURRENT health as Blast.
   Strength - Damage
   Range - Radius
   Duration - Duration of DoT

3. Gloom
   Activate to enable a radial buff slowing enemies and applying lifesteal to allies.
   Life Steal is universal and applies to abilities as well.
   Remains active on Sevagoth even when in Exalted Form.
   Energy drain is based on enemies affected to a maximum of 10 enemies/ 7.5 energy/second.
   Gloom fills Death Well by .1% per second per enemy alive in radius.
   Strength - Slow and Life Steal %s, 272% for 95% slow.
   Range - Radius
   Duration - Radius

4. Exalted Shadow
   Usable once Death Well > 75%
   Drains 1% of Death Well /Second
   Can be reactivated to resume control of Sevagoth.
   Sevagoth will heal 1% Health/1% Death Well consumed upon Reunite.
   Strength - Shadow Claw damage (Sevagoth, NOT Shadow)
   Range - N/A
   Duration - N/A