Turbine's Lord of the Rings Online is the only MMO based in JRR Tolkien's Lord of the Rings universe. What's more, LOTRO is entirely free to play and passionately supported by the developers.
A prime example of said support is the Book 3, Echoes of the Dead update that just went live last week. The content update brings new content to the game, including: new instance clusters, new skirmishes and the continuation of the epic story. For full details, check out our update notes.
Turbine, today, released some brand new screenshots of Ost Dunhoth, a '12-player raid featuring 2 tiers of difficulty with an optional Challenge Mode quest6, two 6-mans and a 12-man raid'. Check the screens out below.
Lord of the Rings Online is free to play, and the content update featuring Ost Dunhoth is live now so definitely jump on in if you're interested. More info can be found at http://www.lotro.com.