Most played cards in Domain:

3 Decks
Chromatic Sphere
12 copies – 4 avg
Evasive Action
12 copies – 4 avg
Swords to Plowshares
12 copies – 4 avg
Fact or Fiction
11 copies – 3.67 avg
Pernicious Deed
11 copies – 3.67 avg
Windswept Heath
11 copies – 3.67 avg
Rampant Growth
9 copies – 3 avg
Flooded Strand
7 copies – 2.33 avg
Gaea's Blessing
7 copies – 2.33 avg
Krosan Tusker
6 copies – 2 avg
Decree of Justice
5 copies – 1.67 avg
Phyrexian Furnace
5 copies – 1.67 avg
Annul
4 copies – 1.33 avg
Duress
4 copies – 1.33 avg
Polluted Delta
4 copies – 1.33 avg
Accumulated Knowledge
4 copies – 1.33 avg
Burning Wish
4 copies – 1.33 avg
Oath of Druids
4 copies – 1.33 avg
Global Ruin
3 copies – 1 avg
Hydroblast
3 copies – 1 avg