How about having a clan actions leaderboard that runs for the duration of each event cycle. This leaderboard would be individual to each clan and rank each clan member by number of actions. (By action I mean Att/Ass an EB or any PvP hit adds 1 point to the clan members score.) A clan members score is set to zero if they leave the clan (except for war). At the end of the event the top 25 get rewards be that tokens or gold bars. Reward could be linked to gold earnt by clan over event. If rewards set at right levels may give players an incentive to stay in clan rather than hop.