There are dozens of secrets in Baldur’s Gate 3, and Ansur’s Lair is one of them. According to Duke Ulder Ravengard, there is a Wyrm located beneath the city that is obliged to help protect Baldur’s Gate when called upon, but only for a single time. That Wyrm’s name is Ansur, and Ulder Ravengard gives you a book that offers information on how to reach it.
Unfortunately, the Duke doesn’t have all of the details figured out and has left the heavy lifting up to you. All you know from reading the Duke’s book is that you need to travel to the Wrym’s Rock Prison and the entrance will be revealed. This took me quite a while to decipher, but I finally managed to do it.
To see exactly how to get inside Ansur’s Lair and find out the mystery behind the dragon in BG3, check out the guide below.
Finding the entrance to Ansur’s Lair in Baldur’s Gate 3
Traveling to Wyrm’s Rock Prison is done by going through Wyrm’s Rock Fortress or taking the sewers underneath the city. You might want to be cautious, though, as if you know about Ansur, then you had to break Ulder Ravengard out of the Iron Throne prison. This will have made Lord Gortash and his followers at Wyrm’s Rock extremely upset, and they will treat you as a hostile when you enter the fortress. I recommend taking the sewers if possible so you can avoid all of the combat. Of course, you can also go through the fortress and deal with Gortash’s army and the rest of the combatants sooner rather than later.

Either way, once you reach the prison, you will likely have to defeat some prison guards. After that, take the first left down the hallway and all you will see are some crates and a wall with a brick out of place. You might also notice a Dragon Head Torch on the left side of the wall. This torch has a brother facing the opposite way on the other wall as well.
Related: Baldur’s Gate 3: How to open Bhaal’s Door in the Undercity Ruins in BG3
All you need to do to open Ansur’s Lair is use any lightning spell on these two torches. This will turn their flames from orange to blue, and once they are both lit, will reveal a secret entrance through the wall. If you don’t have a character with a lightning spell, you could use a scroll as well. I had Gale in my party, so all I had to do was use Shocking Grasp on both of the torches.

And that’s all you need to do to enter Ansur’s Lair in Baldur’s Gate 3. You can keep heading down the path to reach four different Chamber areas, which need to be completed if you want to find Ansur and complete the Duke’s quest in BG3. I explained how to pass some of those Chambers in recent guides, which you can check out to make your time in the lair a little easier.