History of Soulfire Rancor

Soulfire Rancor is a Cull's Shadow catalyst. It is the reward from the chest at the end of Oblation: Soulfed, one of the Oblation missions on the Moon.

Acquisition

First complete Oblation: Bloodline to obtain Cull's Shadow. Use Cull's Shadow to shoot the three rune symbols on the locked door, which unlocks Soulfire Succor and starts Oblation: Soulfed.

In the mission, throw Soulfire Worms at the crystals and kill Soulfire Vessels to collect Soulfire Charges for the pyres. In the boss room, kill the adds to spawn a Soulfire Vessel, then throw a worm onto the middle crystal to start a damage phase against the Ogre. Defeat the Wizard and the Knight the same way. The chest spawns at the end and contains the catalyst. The chest may not spawn if the boss is killed too quickly, so complete the worm-throwing and detonation steps before the final blow.

Completing the mission while Cull's Shadow is equipped also unlocks Soulfire Zeal and a terminal for Oblation: Immolation.