Most played cards in Grixis Control:

2 Decks
Mystical Teachings
6 copies - 3 average
Mana Leak
6 copies - 3 average
Glimmerpost
4 copies - 2 average
Doom Blade
4 copies - 2 average
Cloudpost
4 copies - 2 average
Counterspell
4 copies - 2 average
Sea Gate Oracle
4 copies - 2 average
Dismal Backwater
4 copies - 2 average
Dimir Aqueduct
4 copies - 2 average
Think Twice
4 copies - 2 average
Curse of the Bloody Tome
4 copies - 2 average
Electrickery
4 copies - 2 average
Chainer's Edict
3 copies - 1.5 average
Negate
3 copies - 1.5 average
Preordain
3 copies - 1.5 average
Expedition Map
3 copies - 1.5 average
Ghostly Flicker
3 copies - 1.5 average
Diabolic Edict
3 copies - 1.5 average
Compulsive Research
3 copies - 1.5 average
Ancient Grudge
3 copies - 1.5 average