These are the items that block progress until you know where to get them.
- Elevator Parts: Find all 3 Elevator Parts in The Drains in Well Dweller: top right above the gold key gate, far bottom left, and above the tent by the broken lift.
- Golden Feathers: All 7 Golden Feathers in Well Dweller come from bosses and events, not room pickups. Queen's Castle opens at 7/7. Here's which events give one.
- Looter Parts: Find all 4 Looter Parts in Well Dweller behind golden gates: legs in Graven Valley, arms in the Desiccated Castle, torso in The Drains, head in The Bog.