Playable troops, buildings, and spells are represented as cards. Prior to each battle (with the exception of the first battle in Training Camp), players construct a deck of eight cards which they use to attack and defend against their opponent's cards. At the start of each game, both players begin with four randomly chosen cards from their deck of eight, except Mirror and Elixir Collector.

Each card costs a certain amount of elixir to play. Players start the battle with 5 elixir points (0 in Double and Triple Elixir modes), and one elixir point is replenished every 2.8 seconds (or 1.4 seconds in the final 60 seconds of the game and the first minute of overtime, and every 0.7 seconds during Triple Elixir mode and the last minute of overtime), with a maximum of 10 elixir points. Once a card is played, a new card is automatically drawn from the player's eight card deck.