Most played cards in Threshold:

2 Decks
Meddling Mage
8 copies - 4 average
Force of Will
8 copies - 4 average
Werebear
8 copies - 4 average
Wasteland
8 copies - 4 average
Brainstorm
8 copies - 4 average
Null Rod
8 copies - 4 average
Swords to Plowshares
7 copies - 3.5 average
Stifle
7 copies - 3.5 average
Nimble Mongoose
7 copies - 3.5 average
Tundra
6 copies - 3 average
Naturalize
6 copies - 3 average
Tropical Island
6 copies - 3 average
Polluted Delta
6 copies - 3 average
Flooded Strand
6 copies - 3 average
Misdirection
4 copies - 2 average
Daze
4 copies - 2 average
Compost
3 copies - 1.5 average
Hydroblast
3 copies - 1.5 average
Peek
3 copies - 1.5 average
Winter Orb
2 copies - 1 average