Most played cards in Twiddle Vault:

4 Decks
Twiddle
16 copies - 4 average
Howling Mine
16 copies - 4 average
Volcanic Island
15 copies - 3.75 average
Tropical Island
14 copies - 3.5 average
Hurkyl's Recall
13 copies - 3.25 average
Time Vault
13 copies - 3.25 average
Recall
12 copies - 3 average
Sylvan Library
12 copies - 3 average
Red Elemental Blast
12 copies - 3 average
City of Brass
12 copies - 3 average
Blue Elemental Blast
11 copies - 2.75 average
Mana Vault
9 copies - 2.25 average
Mana Short
9 copies - 2.25 average
Counterspell
8 copies - 2 average
Transmute Artifact
7 copies - 1.75 average
Shivan Dragon
6 copies - 1.5 average
Tranquility
6 copies - 1.5 average
Boomerang
6 copies - 1.5 average
Underground Sea
5 copies - 1.25 average
Regrowth
4 copies - 1 average