Putting -X/-X on creatures means that you might be able to save your own creatures from being removed from the board while getting at your opponents smaller creatures
Its a great way to completely refill your hand in a single turn, which helps aggressive builds continuously apply pressure through the game and prevents you from stalling out or going hellbent at basically any point
Each deck also comes with a 2-card Collector Booster Sample Pack (contains 1 Traditional Foil or nonfoil alt-border card of rarity Rare or higher and 1 Traditional Foil Uncommon card), 10 double-sided tokens, 1 deck box (can hold 100 sleeved cards), 1 strategy insert, and 1 reference card.
But at its most basic, chaos prevents that
Part of the deck building experience was making use of the cards you had in your collection, working with what you had to build the best deck you could from whatever you had access to
13: Same as above, but a different number Flying Pikachu Lv