Most played cards in Humans:

1 Decks
Kitesail Freebooter
4 copies - 4 average
Thalia's Lieutenant
4 copies - 4 average
Ancient Ziggurat
4 copies - 4 average
Meddling Mage
4 copies - 4 average
Mother of Runes
4 copies - 4 average
Champion of the Parish
4 copies - 4 average
Wasteland
4 copies - 4 average
Cavern of Souls
4 copies - 4 average
Aether Vial
4 copies - 4 average
Thalia, Guardian of Thraben
4 copies - 4 average
Unclaimed Territory
4 copies - 4 average
Noble Hierarch
4 copies - 4 average
Mantis Rider
3 copies - 3 average
Karakas
3 copies - 3 average
Dark Confidant
3 copies - 3 average
Hostage Taker
2 copies - 2 average
Grafdigger's Cage
2 copies - 2 average
Mindbreak Trap
2 copies - 2 average
Ethersworn Canonist
2 copies - 2 average
Reflector Mage
2 copies - 2 average