Kill The Depraved Trinity(location: The Rotting Core)
Completion
You have killed The Depraved Trinity. Now talk to Lilly to gain access to Act 10.
Recurring Nightmare Walkthrough
1. Find Trarthan Powder
Location: The Refinery
Trarthan Powder is a quest item located in The Refinery in Act 9. It was located in a Theurgic Precipitate Machine that behind the boss room of the area.
2. Find Basilisk Acid
Location: The Boiling Lake
Basilisk Acid is a quest item that was dropped from The Basilisk of The Boiling Lake in Act 9.
3. Kill The Depraved Trinity in The Rotting Core
Deliver Trarthan Powder and Basilisk Acid to Sin(location: The Quarry).
Sin has burned open a new entrance into the The Belly of the Beast. Enter, and meet Sin at the Black Core.
Travel to The Rotting Core and Kill the final boss: The Depraved Trinity