Baldur's Gate 3 takes place in an extensive world for players to explore, full of monsters to fight, enemies to talk your way past, or people to help. When dealing with the plethora of NPCs in the game, it's important to gather as much information as possible about what's going on; otherwise, you may find yourself helping out the bad guy in a situation.
Upon arriving in the Grymforge, players will be introduced to the Duergar, who have set up camp at the docks. While attempting to explore a nearby temple, the entrance caved in a trapped Nere inside, along with a poisonous gas that is slowly killing him; here is how you can free Nere.
How To Clear The Rubble
The most straightforward method to freeing Nere is to clear out the rubble with an explosion. If you already have an explosive item such as Runepowder or a satchel of Smokepowder, simply throw it at the rubble and ignite it to clear the path. If you need an explosive, listen in on the conversation between the gnomes who are trying to clear the rubble to hear that Philomeen ran off with some Runepowder.
It's also important to note that time is of the essence, as Nere will die after two days in the poison. If you take a long rest, he will communicate with you telepathically and tell you to hurry. If you then take another long rest without freeing him, you'll return to the site of the rubble to find it cleared, with Nere dead and the Duergar nowhere to be found.
Philomeen Hidding Spot
To find Philomeen, return to the Ancient Glyph near the docks. From here, head left to the other side of the docks. Begin circling around the docks until you find a bunch of dead Gnomes and some Duergar trying to clear the bodies. Save your game and pick the lock on the large stone door to enter. Walk to the back left corner of the room and pass a perception check to find a button on the wall. Reload your save to make sure you pass the check and find the button.
After opening the secret passage, continue further down the path until you fight three Ooze enemies. After defeating them, head up the stairs and along the left side towards the edge of the cavern. Jump over to the other side to see a structure ahead with an Ornate Door. Take a second and save your game before heading to the left side of the door and entering the structure from the side.
Here you'll find Philomeen and will need to pass a check of your choosing to ensure she doesn't blow your party up. Failing a check will very possibly result in a party wipe, making your save earlier even more useful. After talking to Philomeen and passing your check, you'll be rewarded with a vial of Runepowder to destroy the rubble. When throwing the Runepowder, be sure to let all the NPCs walk away before igniting the power with some sort of fire.
After Freeing Nere
After Nere has been freed, he'll quickly take his anger out on those around him. While you may be safe from immediate harm, he'll ask for you to get involved in the punishments. This conversation has a lot of options and can go many different ways. Choosing to help the Gnomes will see you fighting the entire camp of Duergar and Nere. Deciding the Duergar don't need punishment will have Nere pay them to help kill you, resulting in the same outcome as siding with the Gnomes. Picking to side with Nere against the Duergar will have him join you in fighting the entire camp. Nere alone is a powerful enemy, so pick your choices carefully and consider who you want to ally yourself with. For those looking for the easiest way through this quest, letting Nere die in the poison by taking two long rests will let you loot his body without having to do any fighting, but also won't be as fun.