Most played cards in The Rock:

3 Decks
Troll Ascetic
12 copies - 4 average
Umezawa's Jitte
12 copies - 4 average
Viridian Shaman
12 copies - 4 average
Aether Vial
12 copies - 4 average
Sakura-Tribe Elder
12 copies - 4 average
Eternal Witness
12 copies - 4 average
Llanowar Wastes
12 copies - 4 average
Llanowar Elves
12 copies - 4 average
Rend Flesh
10 copies - 3.33 average
Persecute
9 copies - 3 average
Hideous Laughter
9 copies - 3 average
Iwamori of the Open Fist
9 copies - 3 average
Terror
8 copies - 2.67 average
Okiba-Gang Shinobi
7 copies - 2.33 average
Naturalize
7 copies - 2.33 average
Nezumi Shortfang
6 copies - 2 average
Ink-Eyes, Servant of Oni
6 copies - 2 average
Pithing Needle
4 copies - 1.33 average
Okina, Temple to the Grandfathers
3 copies - 1 average
Tomb of Urami
2 copies - 0.67 average