Gilded halls is filled with gold. The only way to get there is to sacrifice a least a hundred (I think) gold to that gold circle thing in River. If you sacrifice too little 4 gold skeletons will be spawned and you will be unable to try again. The boss is a gold wizard, after you beat them a portal to Wax World appears at the starting room. A NPC is there, they are puppet.
I hate to be so unprofessional but hopefully this information is useful none the less.
Community notes
A community guide gives the offering as 100 gold to a golden coin-shaped altar and says the "Golden Sacrifice" achievement is awarded when the portal opens. Defeating the Gold Wizard earns its own achievement, and afterward a message says something has changed (see Wax World). See Achievements.
- A thread with developer replies says a golden idol found in a secret room takes roughly 201 coins to open the portal to the Gilded Halls, and the Secret Rooms guide lists the gold altar as unlocked through speaking.
- After the Gilded Halls boss, the message "something on the floor has changed" appears.
Community-sourced (added October 2026, not yet verified in-game). Sources: Steam guide: "every achievement guide" (MSK); Steam thread: Gilded Halls and Waxen Temple (includes developer replies); Steam guide: Secret Rooms and You by Slunky.