In Destiny 2: Shadowkeep, you must clear the Essence of Madness, and you will be rewarded with the legendary Love and Death grenade launcher. The first step is to get to the Gateway House.
Start in Sorrow's Haven and travel to Hellmouth. Find a long black building on the moon's surface where a green light is burning from a doorway in the hallway. Go inside and follow down until you reach the Gateway House.
In the middle of the arena you will find a large Hive Knight: kill him and he will drop the Shackles. The second step of the Essence of Madness quest is to complete 100 kills with a grenade launcher.
