Most played cards in Hammer:

1 Decks
Snow-Covered Plains
7 copies - 7 average
Mox Opal
4 copies - 4 average
Leyline of Sanctity
4 copies - 4 average
Ethersworn Canonist
4 copies - 4 average
Esper Sentinel
4 copies - 4 average
Sigarda's Aid
4 copies - 4 average
Ancient Den
4 copies - 4 average
Colossus Hammer
4 copies - 4 average
Ornithopter
4 copies - 4 average
Puresteel Paladin
4 copies - 4 average
Stoneforge Mystic
4 copies - 4 average
Urza's Saga
4 copies - 4 average
Steelshaper's Gift
4 copies - 4 average
Inkmoth Nexus
3 copies - 3 average
Mana Tithe
3 copies - 3 average
Karakas
2 copies - 2 average
Swords to Plowshares
2 copies - 2 average
Pithing Needle
1 copies - 1 average
Citizen's Crowbar
1 copies - 1 average
Sword of Fire and Ice
1 copies - 1 average