Most played cards in Mardu:

1 Decks
Evolving Wilds
4 copies - 4 average
Dauntless Bodyguard
4 copies - 4 average
Isolated Chapel
4 copies - 4 average
History of Benalia
4 copies - 4 average
Duress
4 copies - 4 average
Midnight Reaper
4 copies - 4 average
Ixalan's Binding
3 copies - 3 average
Clifftop Retreat
3 copies - 3 average
Knight of Malice
3 copies - 3 average
Knight of Grace
3 copies - 3 average
Shalai, Voice of Plenty
3 copies - 3 average
Aurelia, Exemplar of Justice
3 copies - 3 average
Response // Resurgence
3 copies - 3 average
Deafening Clarion
3 copies - 3 average
Lyra Dawnbringer
3 copies - 3 average
Settle the Wreckage
2 copies - 2 average
Sorcerous Spyglass
2 copies - 2 average
Arguel's Blood Fast
2 copies - 2 average
Banefire
2 copies - 2 average
Tocatli Honor Guard
2 copies - 2 average