Most played cards in UR:

3 Decks
Counterspell
12 copies - 4 average
Volcanic Island
12 copies - 4 average
Red Elemental Blast
11 copies - 3.67 average
Serendib Efreet
8 copies - 2.67 average
Lightning Bolt
8 copies - 2.67 average
Chain Lightning
8 copies - 2.67 average
Shatter
7 copies - 2.33 average
Strip Mine
7 copies - 2.33 average
City of Brass
7 copies - 2.33 average
Mishra's Factory
6 copies - 2 average
Fireball
6 copies - 2 average
Psionic Blast
6 copies - 2 average
Power Sink
4 copies - 1.33 average
Ivory Tower
4 copies - 1.33 average
Fellwar Stone
4 copies - 1.33 average
Shivan Dragon
4 copies - 1.33 average
Mind Control
4 copies - 1.33 average
Blue Elemental Blast
4 copies - 1.33 average
Energy Flux
4 copies - 1.33 average
Blood Moon
4 copies - 1.33 average