Exploring the Lower City Sewers or progressing with the main quest will eventually have you stumbling upon the entrance to the Undercity Ruins.
There is a large door that is locked, preventing access and this door cannot be opened by other means unless you solve a riddle or are worthy.
Getting into the Undercity Ruins is vital for progressing with the main quest and opening the door won’t be that hard if you understand the hint that it gives through a riddle.
Undercity Ruins Entrance Location
The entrance to the Undercity Ruins is a door found near the Undercity Ruins waypoint, which is located and cannot be opened using Thieve’s Tools.
The only way to get through is to have proof of Bhaal’s Favor or pay his toll of blood, which is quite easy to do once you figure out the hint.
How To Unlock Door To Undercity Ruins?
If you have not done the Impress The Murder Tribunal quest, you won’t be considered a follower of Bhaal but there is still another way to get in.
You will notice that there are corpses above and will need to attack one of them with a ranged attack.
Stand in the pool of blood that appears, and this will solve the riddle that the door will whisper to you if you have interacted with it.
The door will be opened, and you will continue making your way into the Undercity Ruins without having to repeat this step.
What is Inside The Undercity Ruins?
Upon entering the Undercity Ruins, progressing further will cause a trial to begin and you will need to reach and kill Farslayer of Bhaal Ghislev before he completes his ritual.
The area near Ghislev will mark your party for death, which will instantly kill those who have 100 or less health unless you defeat Ghislev or leave the area of effect.
Defeating Ghislev will allow you to safely pass but there are more enemies in the area that you should be concerned about.
One of the enemies in the area named Strangler Luke has an item called Bonespike Gloves, which is worth looting before you defeat Ghislev.
Once Ghislev has been defeated, the area will be safer as your party won’t instantly die from his ritual but his death also causes the other bodies to disappear, which includes their loot.
During the fight, Ghislev will teleport to Manglin’ Abby who tends to knock her enemies into the chasm, so watch out for her.
If you notice the pathway where Manglin’ Abby was waiting, there is a Metal Door inside, and this allows you to make your way to the Temple of Bhaal.
There are few chests in the area, such as the ones that can be found where the other ambushers have taken position if you feel like picking up a few extra sources of Gold.
Verdict
Getting into the Undercity Ruins will eventually allow you to make your way to the Temple of Bhaal, where Orin the Red is confronted.
It is possible to leave combat to avoid being detected by Ghislev, which will allow you to sneak around and even loot the bodies of your enemies.
If you attempt to defeat Ghislev right away, the other enemies will tend to disappear, which will prevent you from looting them. (Same goes with dead bodies)