Ancient Design is Thrain's hardmode quest for Golem.
- Defeat 10 Lihzahrds or Lihzahrd Crawlers.
- Give Thrain 2 Lihzahrd Power Cells.
- Talk to Thrain. He gives you a Golem Map.
- Enter Golem's domain.
- Defeat Golem.
- Return to Thrain to complete the quest.
- The code comments indicate this quest will likely get a more bespoke temple interaction later.