Most played cards in Oath:

3 Decks
Force of Will
12 copies – 4 avg
Brainstorm
12 copies – 4 avg
Oath of Druids
11 copies – 3.67 avg
Polluted Delta
10 copies – 3.33 avg
Duress
10 copies – 3.33 avg
Funeral Pyre
9 copies – 3 avg
Tropical Island
8 copies – 2.67 avg
Flooded Strand
8 copies – 2.67 avg
Underground Sea
7 copies – 2.33 avg
Tormod's Crypt
5 copies – 1.67 avg
Tundra
5 copies – 1.67 avg
Swords to Plowshares
5 copies – 1.67 avg
Mana Drain
5 copies – 1.67 avg
Sylvan Library
4 copies – 1.33 avg
Ancestral Recall
3 copies – 1 avg
Time Vault
3 copies – 1 avg
Regrowth
3 copies – 1 avg
Vampiric Tutor
3 copies – 1 avg
Time Walk
3 copies – 1 avg
Balance
3 copies – 1 avg