Most played cards in Sygg, River Cutthroat:

3 Decks
Brainstorm
3 copies - 1 average
Spell Snare
3 copies - 1 average
Spell Pierce
3 copies - 1 average
Counterspell
3 copies - 1 average
Snap
3 copies - 1 average
Vendilion Clique
3 copies - 1 average
True-Name Nemesis
3 copies - 1 average
Preordain
3 copies - 1 average
Oona's Prowler
3 copies - 1 average
Pestermite
3 copies - 1 average
Spellstutter Sprite
3 copies - 1 average
Daze
3 copies - 1 average
Duress
3 copies - 1 average
Go for the Throat
3 copies - 1 average
Muddle the Mixture
3 copies - 1 average
Inquisition of Kozilek
3 copies - 1 average
Mental Misstep
3 copies - 1 average
Gitaxian Probe
3 copies - 1 average
Force Spike
3 copies - 1 average
Vapor Snag
3 copies - 1 average