Search for Laerdan's breastplate
Search for the source of the strange laughter
Once inside Dolendath.
You need to clear the area, and click on the Locker. You will find there are two of these inside, once this is done, a hidden door will open.
Now you will need to fight Goeolgur.
One you enter the room with Goeolgur he will begin talking, and then summon four elite mobs to fight with him, these mobs will HEAL him.
Goeolgur will again summon four more elite mobs when he reaches a morale of 30k, and summon four more elite mobs again when he reaches a morale of 15k.
Pull Goeolgur into the tunnel, he will reset the first pull, so pull him, let him reset and pull again, use your champion/off tank to tank him.
Main tank and crowd control types, like loremaster and etc. Will take the four elites, rest will also fight the elite that the main tank is attacking until all four are destroyed, then group attacks Goeolgur until he gets close to 30k morale, then they go back to the room to fight the next four elite spawns.
Repeat this tactic when Goeolgur reaches 15k morale. After the elites are defeated, Defeat Goeolgur.
This will complete the instance, and you will be able to loot the Ancient Chest for the quest: Chapter 1: The Heraldry of Lindon.