Elite lieutenants of Dol Guldur have been seen patrolling the hostile region of Southern Mirkwood, including Thorang, a spirit trapped within deadly armour.
'I have seen strange lights in the forest, like a storm in the night. There is a servant of Dol Guldur that wields lightning. This is no creature of the living but some sort of sorcery controlled armour. Thorang has no will of its own. It is a shell of evil-imbued metals controlled by ancient, dark magic. You must break the bond the animates this monstrosity.'
Thorang can be found somewhere in Southern Mirkwood.
You should defeat Thorang.