Most played cards in The Rock:

3 Decks
Thoughtseize
12 copies - 4 average
Kitchen Finks
12 copies - 4 average
Treetop Village
12 copies - 4 average
Cloudthresher
11 copies - 3.67 average
Twilight Mire
11 copies - 3.67 average
Llanowar Wastes
11 copies - 3.67 average
Garruk Wildspeaker
10 copies - 3.33 average
Profane Command
10 copies - 3.33 average
Infest
9 copies - 3 average
Fulminator Mage
8 copies - 2.67 average
Devoted Druid
8 copies - 2.67 average
Shriekmaw
8 copies - 2.67 average
Gilt-Leaf Palace
8 copies - 2.67 average
Mind Shatter
7 copies - 2.33 average
Murderous Redcap
7 copies - 2.33 average
Makeshift Mannequin
6 copies - 2 average
Mutavault
6 copies - 2 average
Wren's Run Vanquisher
4 copies - 1.33 average
Chameleon Colossus
4 copies - 1.33 average
Nameless Inversion
4 copies - 1.33 average