Most played cards in KCI / Ironworks Combo:

3 Decks
Great Furnace
12 copies - 4 average
Krark-Clan Ironworks
12 copies - 4 average
Chromatic Sphere
12 copies - 4 average
Fabricate
11 copies - 3.67 average
Tree of Tales
9 copies - 3 average
Ancient Den
9 copies - 3 average
Pentad Prism
8 copies - 2.67 average
Seat of the Synod
8 copies - 2.67 average
Thoughtcast
8 copies - 2.67 average
Roar of Reclamation
8 copies - 2.67 average
Chrome Mox
7 copies - 2.33 average
Second Sunrise
7 copies - 2.33 average
Sensei's Divining Top
6 copies - 2 average
Echoing Truth
6 copies - 2 average
Thirst for Knowledge
6 copies - 2 average
5 copies - 1.67 average
Conjurer's Bauble
5 copies - 1.67 average
Qumulox
5 copies - 1.67 average
Ghitu Fire
5 copies - 1.67 average
Talisman of Progress
5 copies - 1.67 average