History of Essence of Brutality

Overview

This is one of the Nightmare Essence quests from Shadowkeep. It is a Eris Morn / Lectern of Enchantment quest: you buy the Essence at the Lectern in Sanctuary on the Moon, cleanse it by completing the objectives below, then return to the Lectern to turn it into gear. Reward is the Loud Lullaby Hand Cannon. Sources describe the Essences as costing one Phantasmal Core each, and objectives only need completing once per account (later identical Essences auto-complete those steps). The quest was part of Season 8 content; I could not confirm from the sources whether it has since been removed or vaulted, so check in game.

Walkthrough

1. Pick up the Essence of Brutality at the Lectern of Enchantment.
2. Complete 50 activities on the Moon: patrols, public events and Lost Sectors.
3. Defeat 50 combatants with Hand Cannons.
4. Collect the Necromantic Strand in the Hall of Wisdom (one source places it in the Circle of Bones, beside the circular platform near the entrance).
5. Visit the Lectern of Enchantment in Sanctuary to create the weapon.

Rewards

Loud Lullaby, a Legendary Hand Cannon.