On April 25, 2018, Clan Wars were added. A clan war is separated into two days: 'Collection Day' and 'War Day'. To play in a Clan War, a Clan must have a minimum of ten players that are level 8 and above. On Collection Day, each player in a Clan gets to do 3 battles in a variety of game modes, which rotate every month. Upon completing a battle, the player earns cards, which go into their Clan's card collection. More cards are awarded upon winning a battle, and players earn more cards in higher Arenas. For the Clan War to progress to War Day, a minimum of 10 players need to do at least 1 battle each. On War Day, a Clan is matched with 4 other Clans with a similar number of participants and Clan Trophies.
Each participant gets to build a deck using only the cards that their Clan unlocked on Collection Day. Card levels are limited to the player's card level and the amount of duplicate cards gained on Collection Day, with the lowest level having priority. Players also must have a card unlocked in their own collection to use it. Players use the deck they built in 1 battle (sometimes 2). Each clan is ranked from 1st to 5th place based on the amount of wins they have, with the rank decided by the number of Crowns each Clan has in the event that two Clans have the same amount of wins.
At the end of the War Day, all players that participated in the War receive a War Bounty containing Gold and sometimes Gems or Trade Tokens. Based on the War rank, Clans lose or gain a certain amount of Clan Trophies. Clans progress through Clan Leagues by gaining Clan Trophies, and higher leagues result in better rewards.
