Most played cards in Cephalid Breakfast:

3 Decks
Flooded Strand
12 copies - 4 average
Cephalid Illusionist
12 copies - 4 average
Brainstorm
12 copies - 4 average
Stoneforge Mystic
12 copies - 4 average
Aether Vial
12 copies - 4 average
Force of Will
11 copies - 3.67 average
Nomads en-Kor
10 copies - 3.33 average
Narcomoeba
9 copies - 3 average
Daze
8 copies - 2.67 average
Cabal Therapy
8 copies - 2.67 average
Polluted Delta
7 copies - 2.33 average
Tundra
7 copies - 2.33 average
Ponder
7 copies - 2.33 average
Swords to Plowshares
6 copies - 2 average
Underground Sea
5 copies - 1.67 average
Marsh Flats
5 copies - 1.67 average
True-Name Nemesis
4 copies - 1.33 average
Dig Through Time
4 copies - 1.33 average
Leyline of the Void
4 copies - 1.33 average
Meddling Mage
4 copies - 1.33 average