How about Clan sieges! Same rules as normal sieges, with a little added strategy. Clan leaders choose teams before each defense/attack with these rules...
Match ups are done by average rating. The defending team must always have equal or better odds but it is the attacking team that choose which players will face off. So, the running order of things would be...
1.Attacking clan captain chooses a match up with the defending clan. This match up can involve as many players as he chooses. The match up must have a level rating average, otherwise the attacking clan must forfeit rating points. In this way the defenders have the high ground, shall we say...
2.The defending team captain checks the match up but cannot change who plays who (this is the right of the attackers, who can choose where to strike!). This disadvantage is counterbalanced with the high ground and a 'wild card'. With this the defending captain may remove one player from his line up if doing so is advantageous to his defense. However, this card cannot be used if there are 3 or less players involved in the battle.
Sound good?
In fact, come to think of it, why not give every clan it's own home castle. Only one defense can take place at a time, but the clan builds up defense medals, the highest total of straight victories/draws, gives the clan a new 'Valour' Stat. This would be a good marker of how good a clan is, regardless of the quantity of games they do or don't play. 🙂