Most played cards in Child of Alara:

4 Decks
Necromancy
4 copies - 1 average
Gitaxian Probe
4 copies - 1 average
Intuition
4 copies - 1 average
Force of Will
4 copies - 1 average
Arid Mesa
4 copies - 1 average
Griselbrand
4 copies - 1 average
Wooded Foothills
4 copies - 1 average
Underground Sea
4 copies - 1 average
Tundra
4 copies - 1 average
Volcanic Island
4 copies - 1 average
Watery Grave
4 copies - 1 average
Windswept Heath
4 copies - 1 average
Duress
4 copies - 1 average
Entomb
4 copies - 1 average
Mystical Tutor
4 copies - 1 average
Unburial Rites
4 copies - 1 average
Brainstorm
4 copies - 1 average
Reanimate
4 copies - 1 average
Remand
4 copies - 1 average
Toxic Deluge
4 copies - 1 average