Several Elves and Rangers have been taken prisoner by a sorcerer within the ancient Elf-ruins of Dannenglor.
The doors of Dannenglor have been sealed. To infiltrate the ancient ruins, you will have to enter through the lower courtyard and work your way up.
The heart of Dannenglor is a large open courtyard with a southern gate, western bridge, and eastern terrace. All three of those will need to be in your control to advance.
The small upper courtyard is the only thing keeping you from the sorcerer.
To take Dannenglor for the Golden Host and free its prisoners, the sorcerer residing here must be defeated and his chamber claimed.