You are playing campaign mode.

Setup: Each player may change hero cards without incurring the +1 threat penalty. Remove each burden with the following burden set icons from the encounter deck:

A Shadow of the Past, Flight to the Ford, The Ring Goes South

"The shield–wall was broken. Erkenbrand of Westfold has drawn off those men he could gather towards his fastness in Helm's Deep." –Ceorl, The Two Towers

Resolution: Each player with a copy of Poisoned Counsels in his hand, deck or discard pile has earned that burden. Add the earned cards to the campaign pool.

Down through the breach of the Dike charged the king's company. Down from the hills leaped Erkenbrand, lord of Westfold. Down leaped Shadowfax, like a deer that runs surefooted in the mountains. The White Rider was upon them, and the terror of his coming filled the enemy with madness. The wild men fell on their faces before him. The Orcs reeled and screamed and cast aside both sword and spear. Like a black smoke driven by a mounting wind they fled. –The Two Towers