In the near-end of Baldur’s Gate 3’s first act, you’ll be faced with two equally tantalizing options: go to Moonrise Towers via the Mountain Pass, or go to Moonrise Towers via the Underdark. Then, if you choose the latter, you’ll have multiple options as far as how to actually enter the Underdark. I would argue one of the easier options lies in the Goblin Camp, through the Defiled Temple.
But, the Defiled Temple has one specific puzzle that could cause some players to cry out in frustration, and that’s known amongst the community as the Moon Puzzle. So, let’s go over the two methods you can use to bypass this puzzle — the correct way, and the smart/lucky way.
The correct way
OK — let’s go over the puzzle from scratch. There are four large circles, or moons, overlapping with each other. These four moons each have four orbs attached, but due to them being overlapped, there are only twelve orbs total. Four of these orbs are dark, while the others have been lit up. If you interact with any given circle, it will spin counter-clockwise.
Your goal is to move the four darkened orbs to the bottom circle — to be clear, because this tripped me up, it’s the bottom circle when looking northward. I don’t know why that tripped me up, but it did. In any case, you’ll quickly see how the darkened orbs are transported; if there’s one on the top circle, spin it until it’s touching the left or right circle, and then spin it again until it’s touching the bottom circle. It’s a little complicated to explain but once you put it into action you’ll see it’s not as hard as it sounds.
As soon as the darkened orbs are all on the bottom circle, a door to the north should open, revealing a passage to the Underdark and to the Selunite Outpost.
The smart/lucky way
If you don’t feel like dealing with the puzzle and want to brute force it, I completely understand. I used this method at first because — as said above — I got flipped around with the puzzle itself. If you have enough points in passive Perception, someone in your party will point out a lever near to the door that you would’ve unlocked by completing the Moon Puzzle.
You’ll need some lockpicking tools (and a bit of luck) to try your hand at unlocking this lever. If you can overcome the difficulty class 15 in Dexterity, you’ll be able to open the door without completing the Moon Puzzle. That said, if you’d rather just complete the puzzle, that’s also valid.
