The Gostannon guards the way between the Mirk-eaves and the Dourstocks in the east. It allows the Enemy passage to reinforce their armies in the Mirk-eaves.
'We must ensure that the commanders in Dol Guldur cannot get reinforcements into the Mirk-Eaves during our assault upon the fortress.
'Any large number of troops would have to come through the Gostannon, the gate upon the road that leads to the east. The Orcs still control it for now, but I am certain that we will soon capture it as well.
'For the moment, I need you to see that the gate is made useless to them. Try to jam the mechanism by which it is raised and lowered on this side. It will not slow them down for long, but by then our assault will be complete and the Mirk-eaves will be ours.'
The Gostannon lies in the north-west corner of the Mirk-eaves, some distance to the east of Echad Sirion.
Fuirgam has asked you to jam the mechanism of the Gostannon to delay enemy reinforcements from coming out of the east.
Fuirgam's Aide is at Echad Sirion, west of the Gostannon.
You should return to him with your report.