The Nin-In-Eilph nightmare quest is an awfully hard one. The Marsh-Dweller is in the staging area to begin with, becoming a threat wall with every passing round until you deal with it. Your threat increases faster than normal, so failing a quest can be particularly punishing. With the wrong shadow card any enemy can make an extra attack. This means a quick, aggressive approach is called for, so I built this deck for the job.
Beorn can be our defender up to a point, but we have some defensive allies to cover it as well. Feint and The Wizards's Voice are good ways to avoid the Dweller's attack altogether, taking away any chance of it being provided a second attack. With Éowyn and Beorn we will have enough to take out the Dweller on the first turn! Then it becomes important to gather some cheap(ish) allies with high .
Questing is accomplished quite well with Éowyn and Arwen Undómiel and the high allies. Dunedain Hunter is a proxy for Dunedain Pathfinder from Race Across Harad.
This deck won two out of six times, though winning is doable it is still hard at times. This is one of those nightmare quests that seems to be more possible with a specific and abnormal approach. At least I got to experiment with tactics Eowyn, she definitely is great for taking down the huge enemies.