After you have carved a path through a significant number of soldiers, looted the wrecked ship nearby, and dealt with the female troll by either killing her or taking a more diplomatic approach, you will be ready for the second part of the Siege of Vergen quest. Get ready to head forward and fight more soldiers. Keep walking down the linear path and you will soon come upon the female troll’s male counterpart. He will inquire about the female troll. You can tell him outright if you killed her, which will provoke him into attacking you. In this case, watch out for the troll’s heavy attacks and dodge around to his flanks and back to attack with quick strikes. The troll may be powerful, be he is also slow, and by hitting frequently and quickly you can beat him easily enough. This is not the best option, though. You will be better off if you spared the female troll and helped her out against the soldiers. In this case, tell the male troll that you helped his female friend, and that she will be safe as long as she steers clear of the Kaedweni soldiers milling about the area. In this case, the male troll will do you a solid by rushing the gates of Vergen, distracting the soldiers so that you may get inside of the tunnels leading into the city.
Follow the path as it loops around to the left to reach the entrance to the tunnels. Run through the valleys in this area and head inside of the tunnels. It will be very dark in the tunnels, and you will have a lot of trouble seeing your feet in front of you if you don’t meditate and drink a Cat potion right away. Down one of these potions to increase your night vision capabilities to a great capacity. The tunnels will be basically a straight line for the first portion, so simply follow the dark path deeper into the tunnel until you come upon a group of soldiers. The enemies will be lead by Adam Pangratt, the mercenary from the camp who you encountered briefly earlier. In typical villain fashion, Adam will prefer to leave the dirty work to his henchmen. He will back into the caves and make his escape while his guards attempt to stop you from progressing any farther.
There will only be a few enemies here, so you don’t have to worry overmuch about tactics or strategy in this battle. Just don’t let any of the soldiers corner you against the cavern’s walls, and try to parry any particularly heavy blows that come your way. Once the soldiers are dead, you should proceed deeper into the tunnels, into the area where Adam fled. As you advance, you will find that the local wildlife has taken up arms against the Kaedweni soldiers. The Rotfiends that are native to the tunnels will be attacking the Kaedweni soldiers in the tunnels. You don’t necessarily have to fight the enemies in this section until they are done fighting each other. Standing back and watching is a perfectly viable strategy here. Alternately, you can also use the Rotfiends to your advantage. Pick them off from afar, or use hit and run tactics by quickly rolling in and striking the Rotfiends in the back before rolling away again, to kill the monsters and initiate the explosion timer. Remember, when Rotfiends die, they explode. With luck, the explosions caused by the Rotfiends dying might just kill off the Kaedweni soldiers as well. Sweep around the arena and pick off any remaining soldiers after killing the Rotfiends, or after watching the enemies tear each other apart.
Proceed ahead through the tunnels, on the same path that you used to travel through them earlier. The path will split off towards the north at one point, but don’t follow it, as it just loops around towards the beginning again. Instead, stay on the central path, and then head up and to the right when the path branches off again. (Spoiler) This will lead you into a battle against Dethmold, Adam Pangrett, and a small group of mercenaries. (End Spoiler.) This will be a fairly tough battle, so you may want to drink a potion or two before beginning, especially if you have been struggling so far.
Boss Battle: Dethmold, Adam Pangrett, & mercenaries
Dethmold will be the main threat in this battle. As such, you should focus most of your attacks on him. As has already been established, he is a very powerful sorcerer, and not afraid of breaking a law or two to get his way. In this battle, his favorite move will be to cast a protective shield around himself, effectively nullifying all damage that you do to him while it is up. When you see the shield go up, ignore attacking Dethmold and switch your focus to Adam Pangrett. When the shield goes down, return your focus to Dethmold. The evil sorcerer will also cast lightning bolt spells your way. These will deal pretty heavy electricity damage, so use the dodge roll to avoid them when you see them coming. In between the shield and the lightning bolts, rush in to attack Dethmold with quick sword strikes. If you do enough damage to him, you can actually remove him from the battle, which will be a great advantage to you. After removing about one fifth of Dethmold’s total health, he will teleport behind a protective barrier and watch in amusement as Adam Pangrett and his mercenaries try fruitlessly to kill you. At this point in the battle, you have basically won. Just concentrate on Adam’s attacks and don’t become overconfident.
Adam will be a much more straightforward fighter. He will mostly strike at you with his sword, and try to block or dodge your own attacks. You can either parry his attacks, or dodge around them and attack while he is recovering. If you intend to get up close and personal with the mercenary, you may wish to cast Quen on yourself so that you will be temporarily shielded from his sword blows. With Dethmold out of the way, killing Adam should be a piece of cake. The only thing you really have to worry about is being hit from behind or from the sides by his mercenaries.
After you finish off both of the main bad guys, you will be left with Adam, almost dead, and Dethmold behind his protective barrier. Dethmold will quickly teleport away, having decided that your power is too great for him to bother tackling right now. In the siege of Vergen, he has more pressing matters to attend to. (Spoiler) As Adam lies at your feet, you will be given the choice to either kill him or spare him. (End Spoiler.) What you do here has absolutely no bearing on the future of the game, so feel free to do whatever your heart desires. Either way, you will be able to get his sword, called Nevde Seidhe. Don’t neglect to pick it up, as it is a powerful Silver Sword that can cause a bleeding effect and that will cause extra damage to Wraiths. Either take it from him and let him live, or kill him and loot it from his corpse.
Now that you have beaten the bosses, the magic barrier that was blocking your progress will now be lowered. Head through the archway that the barrier protected, and you will soon reach the exit of the tunnels. Get ready for more battle, as the siege of Vergen has only just begun. Now that you are free of the tunnels, you will be plunged into the battle proper.
