Crafting materials and currencies
Obducite in Nightmare Dungeons
Nightmare Dungeons are a repeatable Obducite source for Masterworking equipment.
Nightmare Dungeons opened with sigils; Escalating Nightmare Dungeons are another documented option.
Repeat with another compatible sigil while Obducite remains useful. Sigil rewards vary, so this is a repeatable source rather than a fixed amount per run.
Stop when you have enough Obducite for the next Masterworking goal or clears become inefficient; switch to another documented source.
Open a guide to find other locations and see what the item is used for.
Nightmare Dungeons are a repeatable Obducite source for Masterworking equipment.