This is my first real try to build a deck around the "Keep Watch + Arwen Undómiel + Vigilant Dúnadan" sinergy, to allow your Dúnadan to block all enemies each round.
In order to achieve that, you need to give him Sentinel, and boost his stats. Arwen Undómiel and Wild Stallion are there for this. With them in play, you'll have a Sentinel with deffense 4 and 4 heal Points which doesn't exhaust to defend, and therefore, it can counter-attack then by 3 (or even more if you attach him a Warrior Sword
While Keep Watch is the ideal side quest to sinergy with your buffed Vigilant Dúnadan's, with Thurindir you'll probably have to fetch The Storm Comes, as it is the key card which allow your deck to play Arwen Undómiel and Wild Stallion
Hirgon and Éowyn are the heroes which I find to suit better with the deck purpose, as they provide some willpower and resource acceleration.
The deck is filled with some good tactics allies to get advantage of Hirgon's ability. Also it has some cheap card draw from the lore spirit, as it really need a lot of pices to put together.
This is just a first brainstorming, but I think the deck has potential and it can be easily improved.