A wider array of promo types, symbols, and events were added in this promo block
Of course, you'll need to cast a creature spell every turn in order to see all of these counters, but that's not a difficult metric to meet for many creature-based strategies
For example, there can be cards that appear in one type of booster but not the other
Plus, the Showcase Scroll art version is absolutely gorgeous
Not quite, split second prevents further non-mana activated abilities from going onto the stack until the split second spell resolves
The general categories and ratios are: Lands 34-40 Ramp 10-13 Card Draw 10 Target removal 6-12 Board wipes 2-5 Graveyard Recursion 2 Graveyard Hate 1-2 Tutors 1-2 Finishers/ Surprise /Alternate win conditions 1-2 My personal experience and belief is that there should be at least one more category 10