Most played cards in 4c Rally:

3 Decks
Jace, Vryn's Prodigy
12 copies - 4 average
Windswept Heath
12 copies - 4 average
Nantuko Husk
12 copies - 4 average
Reflector Mage
12 copies - 4 average
Satyr Wayfinder
12 copies - 4 average
Polluted Delta
12 copies - 4 average
Collected Company
12 copies - 4 average
Flooded Strand
12 copies - 4 average
Zulaport Cutthroat
11 copies - 3.67 average
Rally the Ancestors
10 copies - 3.33 average
Catacomb Sifter
9 copies - 3 average
Murderous Cut
8 copies - 2.67 average
Collective Brutality
6 copies - 2 average
Canopy Vista
6 copies - 2 average
Spell Queller
6 copies - 2 average
Gideon, Ally of Zendikar
6 copies - 2 average
Sunken Hollow
6 copies - 2 average
Anafenza, the Foremost
5 copies - 1.67 average
Evolving Wilds
5 copies - 1.67 average
Dispel
5 copies - 1.67 average