By contour
When the sign up is done, there will be a symbol beside your name to illustrate who you support. Then, for about 1 week, there will be something like pk everywhere (but no losing any EXP when dying when killed by opposing supporter). When leaving town, you can be attacked and killed by the enemy (Another Player).(Also, you must be Level 15+ To participate in the war). When dying, you will go back to town as normal.
(Site Owners thoughts)
While loosing no EXP is a nice thought, it needs some sort of consequence for dieing. So I would suggestion leaving in the loss of EXP. Also I think when you die you lose your symbol and you return to a regular player, as in you no longer can participate in Killing other faction members. Also from what I gather you mean to lump all this into regular game play. I'm fine with this, but if for some reason a Bubble fighter happened to loose in the arena by a non faction player would that player lose his/her faction tag? I would say no but thats up to the Devs.
When successfully killing an enemy supporter, you gain points. The lower the level the player you killed, the less points you obtain and Vice Versa. Through accumulating points, you will be able to exchange the points for Rewards ( i.e. Event Sunstone).
(Site owners thoughts)
You say you can use your points to get event suns and moons. If you did do this would the tracking system of the points subtract that from your Factions point score? Or would you lose the points but maintain the score for Bubble. I think the "lose points keep score" thing is more rewarding.
At the end of the war, we will see which side becomes victorious with the most points (kills and points are kept Track, maybe on the Information button on start).
The victorious side obtains a consolation prize (everyone gets 5 Event Sunstones and 5 Event Moonstones,etc.).
To make both sides even (so not all high levels join one side), a Top 3 Players for each side will be announced and they will receive bonus prizes. And the Top Player from Either Side obtains the Best Prize.
(Site Owners thoughts)
A better why to keep high lvls from piling into one side is to have multiple factions, not just bubble and shade, but have each with different lvl ranges. Like one of the tornaments Flyff had a way long time ago.
Then, the pk arena, we can have a massive battlefield. Where enemy Monsters Spawn.