The Hidden Palace of Guizang Formula is a Domain in Genshin Impact that’s initially blocked off by a puzzle.
You can find the puzzle in the middle of Luhua Pool in the Liyue region.
The Domain entrance is below a large blue barrier, and in order to break the barrier, you’ll need to use a Pyro character to light up specific fire pillars. You’ll need Diluc, Amber, Bennett, or Xiangling to light the pillars.
The pillars you have to light are the three standing in front of the tallest structures in the circle, as you can see below.
After you activate these three, the rest will light up and the floor will open, giving you access to the Domain. Once you’re at the bottom, standing on the plate will activate an air current to allow you to fly back up easily.
The Domain has two exploration options: Voyage to the Sanguine Sky and Travels of the Moonlit Venturer, which both give Primogems, EXP, Linyue Shrine of the Depths Keys, and other goodies. Note that you’ll need Adventurer Rank 30 to access Voyage to the Sanguine Sky and Adventurer Rank 35 to access Travels of the Moonlit Venturer.