Stagecoach Security

If a plotted card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

Plot abilities are written “Plot [cost],” which means “Any time you have priority during your main phase while the stack is empty, you may pay [cost] and exile this card from your hand. It becomes plotted.”

Stagecoach Security’s triggered ability affects only creatures you control at the time it resolves. Creatures you begin to control later in the turn and noncreature permanents that become creatures later in the turn won’t get +1/+1 or vigilance.