After an unsuccessful attack by Men and Elves on the fortress of Carn Dûm, the Witch-King contemplates his next move. The audacity of his enemies angered him greatly, and a example should be made. However, Angmar has been significantly weakened, and his next attack needs to be planned in order to prevent failure.
With the help of Morgomir & Kaltdrache, he decides to unleash a terrible plague upon the unsuspecting Arnor, created by his sorcerers. These wicked men, already deeply immersed in the Dark Arts, have become even more powerful due to acquiring the shards of the Palantír; their powers have already been demonstrated in the Battle for Cardolan. However, the Witch-king needs a ground zero from which his diabolical plague will spread. With utter malice, he chooses the most sacred ground in all of Arnor: the Barrow downs. These quiet and dignified monuments of the Dúnedain are essential to the morale of Cardolan, which Angmar is perfectly aware of.
Morgomir & Kaltdrache is to lead the attack on the Barrow downs again. Cardolan's forces, outraged at this desecration, sends its own armies (led by Captain Carthaen) to destroy Angmar's forces even as the Sorcerers begin corrupting souls. Morgomir, however, instructs his Sorcerers to cast their own terrible spells on the Cardolan army, weakening it significantly. To finalize victory, Morgomir summons a tortured, evil ice werewolf to crush the opposition. The Sorcerers complete the plague, and the Barrow Wights are fully created. Captain Carthaen is soon trapped by the Wights, and Morgomir stabs him with a Morgul-blade. And so, Karsh the Whisperer is created.