Most played cards in Affinity:

6 Decks
Disciple of the Vault
24 copies - 4 average
Frogmite
24 copies - 4 average
Great Furnace
24 copies - 4 average
Vault of Whispers
24 copies - 4 average
Arcbound Worker
24 copies - 4 average
Arcbound Ravager
24 copies - 4 average
Cranial Plating
22 copies - 3.67 average
Myr Enforcer
21 copies - 3.5 average
Thoughtcast
20 copies - 3.33 average
Seat of the Synod
20 copies - 3.33 average
Aether Vial
20 copies - 3.33 average
Chromatic Sphere
17 copies - 2.83 average
Mana Leak
16 copies - 2.67 average
Electrostatic Bolt
16 copies - 2.67 average
Blinkmoth Nexus
14 copies - 2.33 average
Shrapnel Blast
13 copies - 2.17 average
13 copies - 2.17 average
Atog
10 copies - 1.67 average
Annul
10 copies - 1.67 average
Darksteel Citadel
10 copies - 1.67 average