Your Clan is matched into Wars, against other Clans based on your Clan’s Trophy count. In other words, all the Clans in a War will have roughly the same amount of Clan Trophies when the War begins.
Clan War or Training & Battle Days
In Clan War, you will be primarily matched with players that have the same King Level as you, no matter the League their Clan is in. For higher King Levels, this matchmaking rule is not as strict as it is for lower King Levels, meaning, you will most likely face opponents that are one, or sometimes even two levels lower or higher than you. In other words, a King Level 9 player should mainly be matched with other King Level 9 players, whereas a King Level 13 player will see a more varied range of King Levels.
To keep the time to find a suitable match as low as possible, matchmaking will expand its search using these parameters: +1 / -1 every 20 seconds
The matchmaking system will also consider your personal performance in Clan Wars when matching you with other players.
Clan War Colosseum
Similar to Clan War, your opponents are players with similar King Levels who are also searching for a match in the Colosseum.