Faction War is a Bonus event that is still being tested by AMS. It happens over the course of two days (there is a day titled "Preparation", however nothing special happens) where 48 battlefields are grouped into 12 factions (or teams) and set to battle against each other.
Here are the rules listed in the event:
Forty-eight battlefields are divided into 12 factions. Occupy buildings to earn points and buffs!
Battle Rules
- During this event, units can only be wounded in battle. In addition, no resources (Paint, Plastic, Electricity, Metal, and Spray) will be lost, and defense facilities will be invalid in battle.
- Wounded units in this event will be sent to the temporary hospital. The temporary hospital has no capacity limit. After the event ends, a certain percentage of wounded units will automatically recover.
- Once a faction has occupied the stronghold on a battlefield, the battlefield color will change to the color of the occupying faction's.
- You can only travel to battlefields (highlighted on the Battle Log page) that are adjacent to your battlefield.
- If an enemy faction has occupied the stronghold on your own battlefield, you can return to your battlefield and take it back.
Building Rules
- Multiple commanders can't occupy a Signal Station; rallied attacks aren't available for the Signal Stations, either.
- You'll stop earning points if you leave the stronghold you've occupied, but you'll remain as its owner.
- You'll stop earning points if you leave the Signal Station you've occupied, and the Signal Station will become neutral again.
Point Rules
- After occupying a stronghold, the occupying commander will earn 500 points every minute. (Points earned will be calculated once the occupant changes.)
- After occupying a Signal Station, the occupying commander will earn 20 points every minute. (Points earned will be calculated once the occupant changes.)
- Explore a Resource Node on the battlefield map to earn 5 points each time.
- Earn 50 points for every 10000 enemy faction Power destroyed.
- Earn 10 points for every 10000 Power destroyed by enemy factions.
- Event points can be used to upgrade event buffs, increasing your Power and wounded unit recovery percentage.
Notes
- After the event is over, it takes 10 min to calculate the results. Afterwar, rewards will be sent out. A certain percentage of wounded units in your temporary hospital will automatically recover (this percentage can be increased by upgrading the corresponding buff on the event page).
- Players with 0 points won't receive the faction ranking rewards.
- Rankings are refreshed every hour.
Tips
- During the technical test, units will only be wounded during battles - none will die.
- During this event wounded units will go to the temporary hospital, which has no capacity limit. The temporary hospital applies even when you are on your own battlefield.
- When the event ends, a certain percentage of wounded units in the temporary hospital will automatically heal to full, starting with high-level units and working down to lower-level units. The rest of the wounded units will go into the normal hospital.
- Transporting to other battlefields will break any aegis you have active. Once you are on the new battlefield you can activate a new aegis.
- During the event, resources such as Paint, Plastic, Electricity, Metal, and Spray cannot be looted by other players. Silver can be looted, and your Officers can be captured if you lose a battle.
- Important note: You only get points by attacking (or being attacked by) Factions that are not your own! If you attack someone in your faction, even if they are from another battlefield, you will not get points! If someone from your faction attacks you, you do not get points!
- You can purchase Faction War Teleports in Items - Store - Other.

Battle Log
The Battle Log is a map of linked battlefields arranged in a double-ringed circular pattern. Each battlefield is connected to three other battlefields. Players can travel to enemy battlefields using the Faction War Teleport item, which is only active during the Faction War event. Players can only travel to battlefields that are owned by their faction, or are adjacent to those owned by their faction. In this way, factions wage war against each other, attempting to occupy as many battlefields as they can.

Temporary Hospital
As mentioned, when you engage in battle with another player (either by attacking them or being attacked) your troops will only be wounded, and none will die. All your wounded troops go to the temporary hospital, which has no capacity limit. As long as you follow some crucial tips below you cannot lose troops during this event!

Buffs
Players earn points according to the schedule listed in the rules, and they can spend those points on the following buffs:
- Wounded Unit Recovery Percentage - this buff increases the amount of wounded units that will automatically recover when the event ends. The percentage starts at 30%, and increases by 5% each level, up to a maximum of 80%. It is relatively easy to increase this buff to its' maximum level, and it saves you incredible amounts of healing resources after the event is over if you follow a few tricks.
- Unit Attack, Defense, and HP - this buff increases your battle capabilities.
- Deployment Capacity Up - during the event you can send more troops out for battle as you increase this buff.
- Marching Speed Increase - during the event your attack march moves faster.
You must spend the points manually to activate the buffs - they do not automatically increase, so if you want to restore more troops at the end, you must increase your Wounded Unit Recovery Percentage with points!
These buffs are only temporary, lasting only until the event is over.
The Wounded Unit Recovery Percentage buff is extremely important in making this event fun, especially because wounded units recover starting with your highest level troops once the event ends.
Strategy
If you prepare for the event, and are able to increase your Wounded Unit Recovery Percentage buff to the maximum of 80%, you can participate in this event with no risk to your troops or resources.
Here's the trick:
Before the event starts, create a ton of level 1 troops. The amount of level 1 troops you will need to create depends on how many high level troops you have that you wish to keep without healing them. If you assume that you will automatically heal the full 80% of your wounded troops, then use the following equation to calculate how many level 1 troops you need to sacrifice:
S = K / 4
where:
S = # troops to sacrifice (lvl 1)
K = # troops to keep (anything higher than lvl 1)
For instance, if you have 400,000 troops that are level 2 and above, you will want 100,000 level 1 troops to sacrifice. This will give you a total of 500,000 troops. Assuming you wound them all, once the event ends you will automatically heal 80% * 500,000, which equals 400,000. The 100,000 low level troops will remain wounded, and go to your hospital at the end of the event. Note that there is no cap to the amount of troops that go to your hospital when the event ends. At that point you can choose what you want to do with them - you can heal them (which will require resources), or you can dismiss them (destroy them) for free.