Trigger the ability on your turn, or with little mana remaining and you can lose out on your extra card
A great strategy is to use different tools for different purposes
So for example, lets say a box has a $50 mythic rare, there is a 1 in 8 chance of opening a mythic rare
The standard Pokmon card dimensions are: Width: 2.5 inches (63 mm) Height: 3.5 inches (88 mm) Thickness: Approximately 35pt Thickness in inches: 0.01 inches Thickness in millimetres: 0.35 mm Because these dimensions are used throughout the Pokmon Trading Card Game, collectors can confidently buy standard sleeves, top loaders, binders, deck boxes, and other storage solutions without worrying about compatibility
You may exile the chosen creatures
For another example, Peasant Levies is another card from my set