This is a slight modification of one of my go-to multiplayer support decks. I brought it to the latest CotR Twitch against Battle of the Pelennor Fields. Sadly, we did not survive the quest, but I was happy with how this deck worked so I figured I'd publish it.
There nothing too tricky to playing this deck. The deck is filled with efficient allies and some card draw to help get them into your hand as quickly as possible. I specifically avoided most unique allies (with a few concessions which can be swapped) so that it can play friendly in ad hoc multiplayer games. Still, the deck packs quite a punch once it gets going. As always, Beorn helps you survive the early game, while the Ents come online.
Eagles of the Misty Mountains, Ghân-buri-Ghân and Grimbold all help with the quest, in addition to having useful secondary abilities. Quickbeam brings excellent versatility at a bargain price, and the Dúnedain Hunter augments our combat while providing a nice combo with Mablung. Honour Guard should be reserved for Beorn, but once the bear is done soaking damage in the early game, the guards combine with the Warden of Healing to form an effective damage control squad.
The crowning achievement of this deck in Battle of the Pelennor Fields was that is was able to take down a War Mûmak - something I had never done before. The bear did enjoy feasting of Oliphaunt flesh.
I like the idea of having Entmoot and the Eagles are coming in the same deck.