The idea is to make 3/4maps with special enemies of various difficulty where faction members who win the war , gets to make his members exp in such places with some increased exp gain.
This would give some clans a reason to fight and create some nice competition and also get the factions to be more active and action filled
Putting a HQ that the challenging factions competing for such places must defend and destroy the opponents one to claim the territory for 1-3days till next challenging faction can fight to claim it away of the previous faction who won the fight.
Hours for such events should to be defined still, and there should be a minimum member ammount in a faction to be able to apply to challenge the previous winning faction (example 20 ppl or more factions to apply) and also minimum lvl 15 of the players to partecipate in it (also those 20 ppl have to be lvl 15 at least)
Other details to polish it should also be applied and to avoid some abuses... this is just the basics of the suggestion