History of Assassin's Lament

How to complete

Earn the Exotic Sword Heartshadow, a random drop from the final encounter (the Nightmare of Caiatl) of the Duality dungeon from Season of the Haunted / The Witch Queen. Owning the dungeon (separately or via the Witch Queen Deluxe Edition) is required.

The drop is low-chance but boosted by dungeon triumphs marked with an Exotic engram icon in the Duality seal:

• Mind Heist: find all 12 Repressed Memories (the easiest).
• Solo Thoughtstealer: clear the dungeon solo.
• Master Thoughtstealer: clear on Master difficulty.
• Perfected Thoughtstealer: solo without dying (per Destructoid).

Run the dungeon repeatedly with these completed. The Heartshadow Catalyst is unlocked afterwards by defeating three Nightmares.

Note: sources are from the Season of the Haunted era; drop mechanics may have changed since.