Most played cards in KCI / Ironworks Combo:

3 Decks
Seat of the Synod
12 copies - 4 average
Krark-Clan Ironworks
12 copies - 4 average
Chrome Mox
12 copies - 4 average
Thoughtcast
12 copies - 4 average
Mana Leak
12 copies - 4 average
Pentad Prism
11 copies - 3.67 average
Myr Incubator
11 copies - 3.67 average
Serum Visions
11 copies - 3.67 average
Darksteel Citadel
11 copies - 3.67 average
Fabricate
10 copies - 3.33 average
Ancient Den
10 copies - 3.33 average
Thirst for Knowledge
10 copies - 3.33 average
Talisman of Progress
9 copies - 3 average
Talisman of Dominance
9 copies - 3 average
Condescend
8 copies - 2.67 average
Great Furnace
8 copies - 2.67 average
7 copies - 2.33 average
Early Frost
7 copies - 2.33 average
Vault of Whispers
7 copies - 2.33 average
Tree of Tales
5 copies - 1.67 average