History of Cull's Shadow

Cull's Shadow is a Kinetic Exotic Fusion Rifle designed to play like a Glaive, with frontal blades. It is the reward for the secret Exotic mission Oblation: Bloodline on the Moon.

Overview

• Archetype: Fusion Rifle with a glaive-like melee/blade play pattern.
• Intrinsic perk: "Soulburn". Final blows or rapid hits with the frontal blades heal you and grant Soulfire Charges, which make fired rounds inflict potent corruption.
• Lore: Teben Grey's quote ties it to the death of Cull.

Acquisition

1. Obtain a Weapon of Sorrow (Thorn, Osteo Striga, Touch of Malice or Necrochasm); Thorn is the easiest, purchasable from the Monument to Lost Lights in the Tower.
2. Run The Scarlet Keep strike to the final encounter with Hashladun, Daughter of Crota and use the Weapon of Sorrow to shoot the matching symbol on the locked gate behind her.
3. Visit four Moon locations and kill the green-aura Totality Legionary at each, shooting the runes top to bottom with the Weapon of Sorrow: Anchor of Light (Temple of Crota), Archer's Line (Shrine of Oryx), Hellmouth (Chamber of Night) and Sorrow's Harbor (K1 Revelations).
4. Return to Sorrow's Harbor and enter the secret room beneath the central stairs to start Oblation: Bloodline. Completing it rewards the weapon.

Note: GameSpot and GameRant describe four and five locations differently; I followed GameRant's list and did not verify in game.

Catalyst

Four catalysts, unlocked by progressing the Oblation mission series (not necessarily back to back): Soulfire Succor (crystals destroyed with the blades refund ammo and charges), Soulfire Rancor (bosses of Oblation: Soulfed; crystals auto-detonate near targets), Soulfire Zeal (opening Oblation: Immolation; damage resistance and speed) and Soulfire Skewer (after the third mission; blades inflict corruption). Per Blueberries; GameSpot lists the same effects only partly.