Destiny's Necrochasm is one of the Exotic weapons returning as part of the game's final update Age of Triumph.
While others come from drops as part of the Weekly Featured Raids Playlist, this Dark Below rifle is part of The Crux of Darkness of quest line, which is a random drop and requires a few steps before it's yours.
How to get the Year 3 Necrochasm in Destiny
To get the Year 3 version of Necrochasm, here's each step in brief:
- Get the Husk of the Pit drop from Hive enemies or Nightfall
- Farm Thrall, Wizards of Knights to get the Eidolon Ally rifle
- Visit the Speaker and Eris at the Tower
- Complete the 390 version of Crota's End, defeat Omnigul in The Will of Crota Strike
- Use 'Essence of the Oversoul' item Eris gives you on the Eidolon Alley to get the Necrochasm
Gamer Network's own Arekkz shows these steps in motion in his YouTube video:
Here are the above steps broken down in further detail.
The Crux of Darkness, farm Thrall Wizards of Knights
To unlock the quest The Crux of Darkness for the Necrochasm, you need to get a Husk of the Pit.
How to get Husk of the Pit and start The Crux of Darkness
This is a random drop that looks like a white engram from Hive enemies, and it's recommended you play story missions and Strikes against the Hive.
Ogres appear to have a higher chance of dropping the item, and it can also drop when completing the Nightfall, so it's not a completely unpredictable process.
Farm Thrall, Wizards or Knights
The Husk of the Pit is actually a weapon with a single perk. Inspecting it will explain what Hive enemies you'll need to kill to power it up. This will either be Thrall, Wizards or Knights.
Reddit user notuobmit has compiled some useful farming spots for each of these enemies if you're struggling to find them easily.
It's said you can dispose of the Husk of the Pit and get another if you want to face against a different enemy type from there, but do so at your own risk.
Once you have killed enough enemies, you'll be notified to upgrade the Husk of the Pit, turning it into the Eidolon Ally legendary auto rifle.
Visit the Speaker and Eris at the Tower
With the Eidolon Alley in hand, time to go to the Speaker, who will give you 25 Motes of Light. You'll also need to visit Eris, who gives you the Ally of the Dark step to power up the rifle further.
How to get Essence of the Oversoul
The next steps are completing the 390 version of Crota's End (specifically The Abyss section at the start, and defeating Crota at the end, which are two seperate steps) and then beating Omnigul as part of 'The Will of Crota' Strike.
It's assumed any version of 'The Will of Crota' will do, and while Crota's End is highlighted in the first Weekly Featured Raids playlist, we suspect choosing it via the director will also tick the requirements for the Essence of the Oversoul.
Use Essence of the Oversoul
With those steps done, you'll receive the Essense of the Oversoul from Eris. Now upgrade the Eidolon Ally all the way to its maximum, and the last node will require the Essence of the Oversoul. Spending it will transform the rifle into the Necrochasm. Good job!