Most played cards in Oath:

4 Decks
Force of Will
16 copies – 4 avg
Oath of Druids
15 copies – 3.75 avg
Duress
14 copies – 3.5 avg
Polluted Delta
14 copies – 3.5 avg
Brainstorm
13 copies – 3.25 avg
Tropical Island
12 copies – 3 avg
Underground Sea
11 copies – 2.75 avg
Funeral Pyre
9 copies – 2.25 avg
Flooded Strand
9 copies – 2.25 avg
Mana Drain
8 copies – 2 avg
Tormod's Crypt
5 copies – 1.25 avg
Tundra
5 copies – 1.25 avg
Swords to Plowshares
5 copies – 1.25 avg
Yawgmoth's Will
4 copies – 1 avg
Mystical Tutor
4 copies – 1 avg
Vampiric Tutor
4 copies – 1 avg
Akroma, Angel of Wrath
4 copies – 1 avg
Tinker
4 copies – 1 avg
Time Walk
4 copies – 1 avg
Time Vault
4 copies – 1 avg