I tried to find a full description of how AW works in the current version. Searching in the forum brings up old posts and I understand things changed in the meantime.
Facts that might (with a somewhat high level of confidence) be true:
- Players must be at least level 12 to participate to the war (EDIT2: added)
- Alliance Leader can opt out for the entire alliance from participating to the war
- Players can opt-out from participating to the war
- Players that are inactive (i.e. do not attack) for two consecutive wars will be automatically opted out for the next war (they can manually opt in again). (EDIT2: Added)
- Defense teams can be changed before the war starts (but not during the war). (EDIT2: added)
- The first 30 most powerful heroes of each players are counted for matchmating with the first 5 weighting more (EDIT2: changed according the official change log)
- The most powerful troop of each color is considered in the matchmaking (EDIT2: changed wording)
- The number of players participating to the war is considered in the matchmking (EDIT2: added)
- The win/loss history is considered in the matchmaking so that a winning alliance will face stronger and stronger opponents and a losing alliance will face weaker and weaker opponnents. (it’s not clear how many previous wars are considered)
- Each Alliance has 1000 points that are divided among the teams depending on their Health points. (EDIT:3: based on health, not power!)
- Bonus points for defeating a team are half of the regular points awarded to the team. (EDIT1: added)
- If a player leaves the Alliance before the war starts, his defense team will stay on the field. (it’s not clear what happens if he rejoins during the war)
- If a new player joins the Alliance after the matchmaking he will enter a “spectator mode” for the war. No defese team will be put on the field for him and he won’t ba able to attack.
- Wars last exactly 24 hours
- Wars start 24 hours after the matchmaking process is completed (EDIT1: clarified)
- All battles in a war follow a war rule (intended to help the defense team) that is triggered when the bar is full. Which rule is used in a war is declared before the war starts and can be one of:
- Arrow Barrage : a barrage of arrows is fired, dealing damage to all the attackers (not sure how much damage is dealt)
- Attack Boost : attack stats of heroes in the defense team are increased (not sure by how much)
Field Aid : health of heroes in the defense team are increased (not sure by how much)
- Heroes can be used only once per war
- Leveling up your defense heroes will not change the power of your team: they’ll use the stats they had when the matchmaking was done. (EDIT2: specified it’s solely for defense)
- Each player can perform six attacks: three are given at the beginning the war, other three after 12 hours.
- If the battle time runs out, the attacker loses (EDIT2: added)
- Battles that are not completed when the war time expires will be carried on until the end and are accounted for in the final score (EDIT2: clarified which “time” is it)
- Team respawn time increases: first time is 6h, then 8h, then 10h
- If all the teams are defeated, they respawn immediately
- War chests are related to Alliances (and not to players)
- Winning gives 5 AW chest points, losing gives 1 AW chest points
- War chests are open when the Alliance has 25 AW chest points
- When the chest opens, each player will get a loot whose content is proportional to the contribution that that player made to those 25 AW chest points.
- If a player exits an alliance and participate to a war with another alliance, his/her contribution the that Alliance War chest is reset to 0. (EDIT 4: from version 18.0)
Did I miss something? Is there a better description of AW somewhere?