Most played cards in Urza:

7 Decks
Snow-Covered Island
28 copies - 4 average
Lion's Eye Diamond
24 copies - 3.43 average
Lotus Petal
24 copies - 3.43 average
Ancient Tomb
24 copies - 3.43 average
Seat of the Synod
24 copies - 3.43 average
Mox Opal
24 copies - 3.43 average
Chalice of the Void
24 copies - 3.43 average
Echo of Eons
24 copies - 3.43 average
Narset, Parter of Veils
23 copies - 3.29 average
Urza, Lord High Artificer
23 copies - 3.29 average
Emry, Lurker of the Loch
23 copies - 3.29 average
Karn, the Great Creator
22 copies - 3.14 average
Mishra's Bauble
17 copies - 2.43 average
Urza's Bauble
16 copies - 2.29 average
Walking Ballista
13 copies - 1.86 average
Force of Will
12 copies - 1.71 average
Sai, Master Thopterist
12 copies - 1.71 average
City of Traitors
10 copies - 1.43 average
Tormod's Crypt
8 copies - 1.14 average
Engineered Explosives
8 copies - 1.14 average