This quest was picked up when Philippa tasked you with retrieving Immortelle, a rare herb found in the tunnels beneath Vergen. Head to the tavern and proceed up to where the guest rooms are located to find Zoltan. You will find yourself dragged into drinking with Zoltan, Dandelion, and the others. During the conversation, the dwarves will inform you that Vergen’s mine has been closed due to, what else, an unusual spike in the aggressiveness of the area’s monsters. You can head out with them to clean up the mines of monsters and pick up the Imortelle along the way.
Before you leave for the mines, you’ll want to visit Earso, the merchant from whom you purchased the Harpy traps during the last mission. He will have some grapeshot bombs, which you will need for another quest that will make itself available once you reach the mines.
Once you’ve stocked up on the necessary items, pay a visit to Cecil. Sheldon can open the mine shaft for you, and from there you can proceed downwards into the mines. Upon entering, you will also receive the quest Hey, Work’s On In The Mines, for which you needed the grapeshot bombs.
The mines themselves are almost maze-like in their layout, but are conveniently locked off in sections so that it’s easier to find your way around. Head straight from the entrance until you come to a four way intersection. Go straight and turn left when the room ends to find a warehouse. It is locked for now, but you can come back and unlock it later. Then turn around and head back to the intersection. Turn left at the crossroads and follow that path all the way to its end, where you will find a corpse. Loot it to get the Upper Shaft Key and the first page of Balin’s Journal. Now go back from the direction you came and head down the right-hand pathway instead. The key you looted from the corpse will open a door here. Unlock the door and follow the winding walkway all the way down until you are met with another locked door. The path to the left will lead you to another corpse, which you should loot to receive the Middle Shaft Key, more pages from Balin’s Journal, and a section of map.
If you haven’t encountered them already, watch out for Rotfiends in this area. After killing them, make your way through the second locked door. You will be faced with a fork in the road. Although both paths eventually lead to the same locked door, you will want to take the left way down, because the corpse with the key is located down this branch in a short offshoot. After looting the corpse of its key and journal pages, unlock the door at the end of the pathway.
Have your Silver Sword at the ready and proceed deeper into the cave. As you near the end of the mines you will stumble upon a Bullvore and a small posse of Rotfiends. Let the Rotfiends focus on attacking your Dwarven allies while you tackle the Bullvore. Use Yrden to trap the beast before attacking it to bring it down quickly. After the battle, loot what you need and proceed to the bushes growing on the outskirts of the battlefield. Pick some Immortelle and prepare to collapse the tunnel.
Retrace your steps to the third of the locked doors, but take the opposite path that you took to get to the Bullvore. When you see a small path branching off from the main route, take it to its conclusion to find the key to the warehouse that you found earlier. Watch out for traps, though, as this path is absolutely littered with them. Disable them and collect them as you go. In addition to the warehouse key you’ll also find the final part of Balin’s Journal, thus completing the story of what happened inside of the mine, and a hunk of rotten meat. Take the meat too, as it attracts Nekkers and can be helpful in a pinch.
On your way out of the mine, be sure to stop by the warehouse and loot it. It contains a very powerful new Steel Sword, the Robust Sword of Dol Blathanna, along with some iron ore and grapeshot bombs. Proceed to the exit, where you’ll say your goodbyes and earn 1,000 experience points.