Most played cards in Mardu:

1 Decks
Bedlam Reveler
4 copies - 4 average
Lightning Bolt
4 copies - 4 average
Faithless Looting
4 copies - 4 average
Thoughtseize
4 copies - 4 average
Lingering Souls
4 copies - 4 average
Marsh Flats
4 copies - 4 average
Badlands
4 copies - 4 average
Young Pyromancer
4 copies - 4 average
Leyline of the Void
3 copies - 3 average
Grove of the Burnwillows
3 copies - 3 average
Cabal Therapy
3 copies - 3 average
Bloodstained Mire
3 copies - 3 average
Punishing Fire
3 copies - 3 average
Hymn to Tourach
3 copies - 3 average
Kambal, Consul of Allocation
2 copies - 2 average
Surgical Extraction
2 copies - 2 average
Marsh Casualties
2 copies - 2 average
Pyroblast
2 copies - 2 average
Wear // Tear
2 copies - 2 average
Goblin Rabblemaster
2 copies - 2 average