No cards are X-listed, all cards are R-listed, and since I haven't found anything about the site path, I think that War of the Ring sitepath would be the most fitting (since basically it is just open, with further restrictions). I don't know about any other restrictions, but depending on playgroups you can define a minimal decksize, for example in MTG's Elder Dragon Highlander, you have to play exactly 100 cards, and 200/250 cards in classical highlander.