Most played cards in Stax:

4 Decks
Ancient Tomb
16 copies - 4 average
Chalice of the Void
16 copies - 4 average
Mox Diamond
12 copies - 3 average
City of Traitors
12 copies - 3 average
Trinisphere
12 copies - 3 average
Wasteland
8 copies - 2 average
Oblivion Ring
8 copies - 2 average
Humility
8 copies - 2 average
Ghostly Prison
8 copies - 2 average
Rest in Peace
7 copies - 1.75 average
Armageddon
7 copies - 1.75 average
Elspeth, Knight-Errant
7 copies - 1.75 average
Crucible of Worlds
7 copies - 1.75 average
Banishing Light
7 copies - 1.75 average
Smokestack
6 copies - 1.5 average
Mishra's Factory
6 copies - 1.5 average
Flagstones of Trokair
6 copies - 1.5 average
Karakas
5 copies - 1.25 average
Batterskull
5 copies - 1.25 average
Thalia, Heretic Cathar
4 copies - 1 average