This describes a decreased cost (draw fewer cards) but increased difficulty (more successes required). If multiple characters are involved in the action, you cannot benefit from this rule if the Action card has a [Red Lock] icon on it.
Note 1: The value of X is chosen by the active player.
Note 2: The rule does not work the other way, by increasing the number of drawn Action cards and decreasing the number of required successes.
Note 3: If the action has a [Red Lock] icon, multiple players can still take the action together without modifying the cost and difficulty.