Most played cards in Stax:

5 Decks
Chalice of the Void
20 copies - 4 average
Ancient Tomb
20 copies - 4 average
Trinisphere
16 copies - 3.2 average
City of Traitors
15 copies - 3 average
Mox Diamond
15 copies - 3 average
Wasteland
11 copies - 2.2 average
Armageddon
11 copies - 2.2 average
Ghostly Prison
11 copies - 2.2 average
Oblivion Ring
10 copies - 2 average
Crucible of Worlds
10 copies - 2 average
Mishra's Factory
9 copies - 1.8 average
Elspeth, Knight-Errant
9 copies - 1.8 average
Smokestack
9 copies - 1.8 average
Rest in Peace
9 copies - 1.8 average
Humility
8 copies - 1.6 average
Flagstones of Trokair
8 copies - 1.6 average
Banishing Light
7 copies - 1.4 average
Thalia, Heretic Cathar
7 copies - 1.4 average
Cavern of Souls
7 copies - 1.4 average
Leyline of Sanctity
7 copies - 1.4 average