this is an idea wich should be implanted in an entire chapter:
1. Basic Idea
the map is spreaded with loads of outposts (they'll be ranked 1-5 or something like that). the basic idea is that every outpost, city and mission can be captured by a guild/alliance.
2. capturing/defending an Outpost
to capture an outpost you have to talk to a specific person in the outpost and submit a challenge to the controlling guild (there's a max of 2 challenges every 24 hours). when the controlling guild accepts your challenge (wich they will have to because they will lose their outpost if they don't accept your challenge within 24 hours) , both you and the controlling guild will have to select the 12 players that will fight (and your alliance ONLY, no guests, no heroes, no henchman) then when both are ready again you start the mission and the 12 people of your alliance will travel to a map depending on the rank of the outpost. every outpost will first be defended by an army of lvl 20-28 npcs depending on the outpost rank. the rank of the outpost and the location determines what map the game will be played on (for example if there are walls, what triggers the gate to open, if there are catapults to bombard the walls, how many and what npcs, wich lvl the npcs are, outposts in snowy terrain will be played on snowy maps etc.)
guilds can buy additional defenses for their outpost when they have enough money (for example 20k for an extra archer (max 5 extra archers)) or buy additional NPCs or war machines or perhaps exploding catapult ammo instead of plain rocks to help them capture an outpost.
3. benefits of controlling an outpost
controlling an outpost will generate taxes, these taxes will be available for the leader of the alliance only! some outposts might have additionals income like a stone quarry wich generates stone materials or maybe a rank 5 outpost with a diamond mine generating diamonds. higher ranked outposts without a stone quarry or mine generate additional taxes. let's say a rank 1 outposts generates 5k each day and every rank upwards doubles the number that would be: 5-10-20-40-80k each day, a material will be the equilevant of how much they are worth at the trader.
4. example outpost map
(i know my paint skills are unmatched but please dun beg for authographes)
quick explanation: this is an very basic example of a rank 4 outpost on grassland terrain. assault team spawns with 3 separate squads who communicate through the team chat (as alliance battles) at their respective spawn points stands a npc of wich they can learn the Light Flare skill wich steers the catapult, the defending team spawns in their fortress. assault team needs to capture the 2 capture points in the fortress (who double as spawn points for the defending team) to conquer the outpost. defending team needs kill all the NPCs (all lvl 30 warriors) who give flare (the ones near the assault spawn points) or perhaps easyer out DP the assault team (assault team gets a morale boost by destroying a gate). assault team needs to repair a catapult with a repair kit to blow up the gate the catapult needs to be steered with light flare to get entrance to the 2 fortress capture points. defending team needs to repair their gates with a repair kit wich yields them a morale boost.
X

I just think there is a little more to it than what has already appeared.
only problem with this idea is it is VERY discriminating against smaller guilds