Most played cards in UG Fog:

3 Decks
Accumulated Knowledge
12 copies - 4 average
Brainstorm
12 copies - 4 average
Tangle
12 copies - 4 average
Moment's Peace
12 copies - 4 average
Arcane Denial
12 copies - 4 average
Jace's Erasure
12 copies - 4 average
Muddle the Mixture
10 copies - 3.33 average
Nourish
9 copies - 3 average
Respite
8 copies - 2.67 average
Ash Barrens
8 copies - 2.67 average
Scattershot Archer
8 copies - 2.67 average
Take Inventory
8 copies - 2.67 average
Ponder
8 copies - 2.67 average
Quiet Disrepair
6 copies - 2 average
Gush
4 copies - 1.33 average
Dispel
4 copies - 1.33 average
Preordain
4 copies - 1.33 average
Radiant Fountain
4 copies - 1.33 average
Thought Scour
4 copies - 1.33 average
Relic of Progenitus
4 copies - 1.33 average