Double Card

The Double Card is an item found exclusively in the Toad Scramble mode of Mario Party: Star Rush. It doubles the amount of coins and Stars obtained when a boss is defeated, and it is stackable, meaning that players can earn up to eight Stars if they defeat the last boss of any board. Unlike other items, it activates automatically as soon as any player faces a boss. Its Balloon Bash counterpart is the Double Star Card.

In-game description

 * "Doubles the Coins and Stars received from a boss battle."