One card that springs to mind is Ram Through which is a green removal spell that also doubles as a burn spell if you have trampling creatures
RMS Titanic is slightly better card, as a 7/1 with trample that crashes into an opponent and gives you loads of Treasure
Tetzimoc, Primal Death is one of my favorites, as is Renata, Called to the Hunt and Master Biomancer, both efficient ways to get counters on your creatures
Karns Bastion Karn's Bastion is usually easy to slot into the mana base of decks with counter themes, even though it doesnt actually get activated often
To identify which is which, we need to use a loupe and closely inspect the cards
Those players who brave the dragonstorms and emerge victorious will make it to Day Two, which features Tarkir: Dragonstorm Draft