Bound Manacle

The Bound Manacle is the quest item for the Essence of Insanity quest in Shadowkeep. It drops from a Hive Knight boss, Ehrath'Ur (also spelled Erath'ur), called the Eternal Blade, in the Gatehouse of the Hellmouth on the Moon. Guides describe the route as a lit path down through the Gatehouse to a boss room, and advise using energy weapons to strip the boss's shield.

The quest's first step asks for 100 Grenade Launcher final blows, then recovering the Bound Manacle once in the Gatehouse. The item is turned in at the Lectern of Enchantment in Sanctuary, which uses Nightmare Essence to create the Love and Death grenade launcher.