Radagast knows the ancient evil of the Gaunt-lord Ivar, called the Blood-hand, who is raising an army of wights in Agamaur.
'You have made quite the name for yourself, ${PLAYER}. Word of your exploits has reached me even here. Indeed, I am surprised with all you have accomplished. Still, perhaps you can assist me again.
'I know what began the plague in Agamaur, the Red Swamp. A Gaunt-lord, a dire creature in the service of Angmar, has raised an army of wights here and has stirred this ancient evil, not the Eglain. I must ask you to intervene on my behalf, for I cannot. Would you go in my stead?
'In the east are the ruins called Garth Agarwen. I would search there for Ivar the Blood-hand. If you find him and defeat him, bring his helm to me as proof.'
Ivar may be found in Garth Agarwen in Agamaur, within the Lone-lands.
Radagast is unable to directly interfere in the war by seeking out and destroying Ivar the Bloodhand. He has asked you to go in his stead and to bring him Ivar's helm as proof of your victory.