Most played cards in Mystic Forge Combo:

1 Decks
The One Ring
4 copies - 4 average
City of Traitors
4 copies - 4 average
Basalt Monolith
4 copies - 4 average
Ancient Tomb
4 copies - 4 average
Grim Monolith
4 copies - 4 average
Leyline of the Void
4 copies - 4 average
Mox Opal
4 copies - 4 average
Voltaic Key
4 copies - 4 average
Karn, the Great Creator
4 copies - 4 average
Defense Grid
4 copies - 4 average
Manifold Key
4 copies - 4 average
Urza's Saga
4 copies - 4 average
Paradox Engine
4 copies - 4 average
Mystic Forge
4 copies - 4 average
Lotus Petal
4 copies - 4 average
Faerie Macabre
3 copies - 3 average
Crystal Vein
2 copies - 2 average
Dismember
2 copies - 2 average
Tormod's Crypt
1 copies - 1 average
Mycosynth Lattice
1 copies - 1 average