Azruthor's forces venture out of Tarlang's Crown including Gundlag, whose lifeless corpse is controlled by The Dead.
'The Sorcerers of Umbar have called forth evil spirits to carry out their orders. Fell spirits under the command of Azruthor's forces have possessed the bodies of many slain beasts.
'One such beast was once a cave-troll, Gundlag. Now it is a colossal creature, not of the living. This beast was a menace even before it was corrupted in death. This fell troll must be dealt with before it ventures out of the woods and into a town.'
Gundlag can be found somewhere in Western Gondor.
You should defeat Gundlag.
Aelnir can be found in the city of Dol Amroth.
You should speak with Aelnir.