It seems that the old Trainer cards were a lot more forgiving, something that was fortunately ironed out in testing
Chase Carter News $3m Black Lotus overtakes 1/1 One Ring to claim Magic: The Gathering's most expensive card record Sold at private auction, the graded Pristine 10 Black Lotus reclaims the pricey throne for an MTG legend
(You can read an analysis of the first-place LuxChomp deck here.) I will touch on every card because, if you are reading this, you probably wont be helped by writer shortcuts that force you to try and figure out how common cards are being played
On the bottom, is Professor Oak's New Theory
While there are other cards beyond those listed that could make a big difference, these are the rares and mythics (not including Triome/Temple lands) that will provide the best returns on investment going into Zendikar Rising
And as a bonus, you get to draw an extra card at the start of your upkeep, while your opponents are on a six-turn clock (not including damage)