Mason gives you a practice deck and your first opponent, Sam
Urabrask will count any instant or sorcery spells you've cast during the turn, whether those spells resolved, didn't resolve, were countered, or left the stack some other way
If you're playing an aggressive or midrange tribal deck and you're only including sixteen creatures, you have to ask yourself: "Is it even worth playing all of these tribal cards in the first place?" If, for example, you only have enough creatures to have a couple in play at any given time, you're not maximizing your tribe's abilities
Counterspells: Opponents may use counterspells like "Counterspell" or "Negate" to prevent your crucial spells with Affinity for Artifacts from resolving
A Precise Digital Scale: A pocket scale that measures down to 0.01 grams will catch bad card stock immediately
When you consider that single-target exile removal is very much costed at six or more on creatures and artifacts, it becomes more reasonable to assess the card