A single Swords to Plowshares would set Anti-Venom back to square one, which is potentially devastating
This one gets a high value as it's special
Ice Age While Ice Age has a number of cards that use +1/+1 and -1/-1 counters, there are only a few cards that I would call innovative (join me next week, by the way, when I talk a little more about innovation and Magic design)
Bear Umbra [Foil] Magic Rise of the Eldrazi Keep track of your collection value over time
Reprints from Across Magic 's History Mystery Booster 2 includes over 1,000 reprints for a draft experience unlike any other
There is most definitely an optimal version of this deck that would include Black Lotus, Mox Sapphire, Time Walk, and Ancestral Recall, but I think this particular deck is a good example of what can be done without those cards