Assault on Dragonspear - Main quest BG: Siege of Dragonspear Guide
Last update: 01 July 2016
This quest mostly consists of fighting. The first battles will take place in the castle but after a while the action will move to an alternative dimension. Below you will find a detailed list of steps related to the game finale.
Taking control over the castle
Report to Torsin de Lancie after you get close to the castle. Tell him what you saw and did while exploring the caves and the basement. Since you placed explosive barrel in the caves, a part of castle walls will be destroyed and allied forces will be able to get into the outside courtyard. Go northwest and join the giant battle on the courtyard. When fighting there, avoid moving too much forward with your team or you can be suddenly surrounded by many enemies or be attacked by too many archers and wizards. Keep fighting until all crusaders are eliminated (they will be weakened if during the visit in the basement you poisoned the water or food supplies).
At first the passage through the inside courtyard will be inaccessible. Because of that you should go northwest where a cutscene of conversation with Ashatiel will start. You can behave in two ways now. If you want, you can participate in regular battle with Ashatiel and her followers. After you defeat her you will be forced to move further to the east and to also defeat Tristian, the leader of a group of crusaders. An alternative option is to accept Ashatiel's proposition and participate in honorable duel one versus one. If you manage defeating her in direct combat (Ashatiel is able to deal powerful crushing damage) then the remaining crusaders will escape.
No matter which method you selected, once all is over you must move towards the inner courtyard of the castle. There you can listen to another speech of Caelar Argent. After the passage to the courtyard becomes unlocked, use it and go north. Look for Dosia from whom you can once again receive free healing. Then look for small passage thanks to which you can get inside the castle. Once you're inside, a rather linear march through castle chambers will start. On the way the team will encounter Belegarm. You can spend all your gold by buying items from him (you won't need the gold later). You must reach the door in the eastern part of the palace. The door will lead to lower floor. Listen to conversation with captain Corwin and go towards the northwestern room where Bence Duncan will be waiting. Enter the new chamber (the vault) and watch the cutscene with Caelar Argent and Hephernaan. Once it is over, enter the portal leading to different dimension.
Journey to different dimension
While traveling through the world of Avernus you will have to face new types of enemies and many of them will be similar to various angels and demons. Near the starting location you will encounter a group of crusaders trying to defeat the monsters. You can help them in winning and then kill them as well or you can then let them leave the place. Once in the next location, start walking in straight line to the northeast. The walk will be harder due to the forced confrontations with new monsters.
Once you get close to the large gate, a new cutscene will start during which you will encounter Caelar. Once the cutscene ends, the party will be stopped by the creature named xxx. The creature will have a proposition. The player can risk the life of one of his companions and try solving a riddle. If you win, then you will receive one of the valuable artifacts. If you lose, then Thrix will take way one of your allies. Of course, you can refuse playing the game proposed by the monster, but in that case you will only make him angry and will be forced to defeat the monsters summoned by him. It is much better to agree on solving the riddle. The correct answer is You speak of murder, devil and it is marked on the above picture. As reward you can select Tongue of Acid +3 sword, The Guardian Devil helmet or Echo of the Fiend +3 magic wand (the demon won't be happy to lose this item).
No matter how you acted during the encounter with Thrix, walk through the giant gate. You will reach the elevator. Before you use it, consider saving your progress because after the elevator trip ends the final battle of the game will start. Once the elevator trip ends, the battle with the final opponents of the game will start. Be ready to face some minor monsters while the elevator moves - they shouldn't pose a threat to your party.